Second review of the night's own code: a stray clears when a later removal works (N2), the start-up check never removes this process's own copy (N3), one copy per destination at a time (N4), RunTier2 refuses during a restore for every caller (N5), the import refusal no longer advises removal (N9); red-proved, race-clean; README; REPORT; unreleased

controller/README.md

@@ -1399,6 +1399,14 @@ retired in v0.126.0 when the moved blocks were legitimately rewritten onto the s
   contain no symlink (`tier2CappedPath`, `filepath.EvalSymlinks(p) == p`: a link could point the mount elsewhere). A
   docker start error (exit 125) falls back to plain rsync; any other failure is returned. Measured on 9202 (4 GB, 1.8 GB
   held, 6 GB copy): full stall 5.7 s → 0.37 s. Tests `r1214_capped_copy_test.go`.
+- **The copy container never outlives the copy (the stray-copy fix, unreleased, rides 0.340.0).** Each copy container has
+  a fixed name (`felhom-tier2-copy-<app>-<8 hex of the destination>`) and the label `felhom.tier2-copy=1`; a leftover of
+  the same copy is removed before it starts, and on any error — the timeout included — it is removed by name. At
+  controller start, BEFORE the scheduler and the web server, every labelled container is removed (logged; retried every
+  minute until it succeeds). A restore is refused while any second-drive copy runs or a leftover may run
+  (`backup.Tier2CopyBlocksRestore` → `restoreOpBlocked`). The run uses `--mount` (a path the daemon does not see is
+  refused, exit 125 → the in-process copy), the controller's image ID with `--pull never`, and `--no-healthcheck`.
+  Tests `tier2_copy_lifecycle_test.go`, `web/straycopy_restore_refused_test.go`, `cmd/controller/straycopy_wiring_test.go`.
 - **A template may leave a named volume out of the app-data backups (unreleased, rides 0.340.0; R-49, operator D21 = B).**
   `.felhom.yml` `backup.volumes: [{name: <volume>, class: excluded}]` — every named volume is dumped except
   `<project>_<name>` (`appbackup.ExcludedDockerVolumes` → `backup.Manager.dumpableVolumes`), so it leaves Tier 1, Tier 2

controller/internal/appexport/restore.go

@@ -364,11 +364,12 @@ func (e *Exporter) executeImport(req ImportRequest, job *Job) {
 	// is a corruption shape), reported as success. Only a running app's volumes are removed first. So this import is
 	// refused here, before anything is written; the household starts the app (or removes it) and imports again. „Not
 	// running" is IsStackRunning's view: running or degraded only, so an unhealthy or restarting app is refused too —
-	// the text says so and names removal (review 2026-10-22 night, C3; the import path for those states is R-1187).
+	// the text says so; it does NOT advise removal, which would lose data newer than the bundle (review 2026-10-23
+	// night, C3 + N9; the import path for those states is R-1187).
 	// Pinned by TestR1187c_AStoppedAppIsNotImportedOver.
 	if isDeployed && !isRunning {
 		e.logger.Printf("[WARN] Import: refused — %s is installed but not running; importing over it would merge the old data with the bundle's (R-1187 c)", manifest.AppName)
-		e.failJob(job, step, "Az alkalmazás telepítve van, de nem fut rendben (leállt, vagy hibásan indul), ezért a csomagot nem töltjük vissza: a régi adatai összekeveredhetnének a csomagéval. Az alkalmazás érintetlen. Ha leállt, indítsd el; ha hibásan fut, távolítsd el. Utána próbáld újra.")
+		e.failJob(job, step, "Az alkalmazás telepítve van, de nem fut rendben (leállt, vagy hibásan indul), ezért a csomagot nem töltjük vissza: a régi adatai összekeveredhetnének a csomagéval. Az alkalmazás érintetlen. Ha leállt, indítsd el, és próbáld újra; ha hibásan fut, kérd az üzemeltető segítségét — ne távolítsd el, mert az adatai a csomagnál újabbak lehetnek.")
 		return
 	}
 

controller/internal/backup/r1180_mirror_during_restore_test.go

@@ -58,3 +58,25 @@ func TestR1180_TheNightMirrorNeverRunsDuringARestoreOfThatApp(t *testing.T) {
 		t.Fatalf("after the restore the mirror must run again, got %v", got)
 	}
 }
+
+// Review 2026-10-23 night, N5: RunTier2 itself refuses during a restore of that app — the config-save and debug paths
+// call it directly. RED-PROOF: with the restoreRunningFor check at the top of RunTier2 removed, this fails — seen
+// failing 2026-10-23 night.
+func TestR1180_ADirectRunTier2NeverRunsDuringARestore(t *testing.T) {
+	m, src, target, prov := newTier2V2(t, "app")
+	prov.has["app"] = true
+	prov.binds["app"] = []ClassifiedBind{mHDD("appdata/app/photos")}
+	m.stackProvider = r1180Provider{prov}
+	called := 0
+	m.tier2Mirror = func(s, d string) error { called++; return rsyncMirror(s, d) }
+	mustWrite(t, filepath.Join(src, "appdata", "app", "photos", "a.jpg"), "a")
+	m.BeginRestoreOp("tier2-whole-restore", "app")
+	if err := m.RunTier2("app"); err != nil || called != 0 {
+		t.Fatalf("a direct run during a restore must copy nothing (err %v, mirror calls %d)", err, called)
+	}
+	m.EndRestoreOp(true, "")
+	if err := m.RunTier2("app"); err != nil || called == 0 {
+		t.Fatalf("after the restore the direct run must mirror (err %v, calls %d)", err, called)
+	}
+	_ = target
+}

controller/internal/backup/r1214_capped_copy_test.go

@@ -23,6 +23,7 @@ func withSeams(t *testing.T, root string, img string, run func(args []string) ([
 	oldRoot, oldImg, oldRun, oldLog, oldDocker := tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker
 	// The copy's lifecycle commands (rm -f by name) never reach Docker from a test (they would act on the host).
 	tier2Docker = func(context.Context, ...string) ([]byte, error) { return nil, nil }
+	tier2RetryOff = true
 	tier2CappedRoot = root
 	tier2SelfImage = func() string { return img }
 	tier2RunCapped = func(_ context.Context, args []string) ([]byte, int, error) {
@@ -32,6 +33,7 @@ func withSeams(t *testing.T, root string, img string, run func(args []string) ([
 	tier2Logf = func(string, ...any) {}
 	t.Cleanup(func() {
 		tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker = oldRoot, oldImg, oldRun, oldLog, oldDocker
+		tier2RetryOff = false
 	})
 	return rec
 }

controller/internal/backup/tier2.go

@@ -340,6 +340,12 @@ func (m *Manager) tier2ReconcileRoots(destBase string, roots, legRels []string)
 // capture legs (§8). Best-effort and idempotent. Records status for the UI; returns an error only on
 // an actual copy failure (no valid target is a recorded status, not an error).
 func (m *Manager) RunTier2(stackName string) error {
+	// R-1180 for EVERY caller (review 2026-10-23 night, N5): the household's „Tier 2 on" save and the debug run call
+	// this directly, outside RunAllTier2's skip — a mirror (rsync --delete) must never start during a restore of the app.
+	if m.restoreRunningFor(stackName) {
+		m.logger.Printf("[WARN] [backup] Tier 2 for %s not started — a restore of it is running; it is mirrored at the next run (R-1180)", stackName)
+		return nil
+	}
 	// Customer turned Tier 2 off for this app (config panel) — skip without touching status.
 	if m.settings != nil {
 		if cd := m.settings.GetCrossDriveConfig(stackName); cd != nil && cd.UserDisabled {
@@ -797,6 +803,10 @@ func rsyncMirror(src, dst string) error {
 	s, d := strings.TrimRight(src, "/"), strings.TrimRight(dst, "/")
 	rs := []string{"-a", "--delete", s + "/", d + "/"}
 	name, app := tier2CopyName(d)
+	// One copy per destination at a time in this process (review N4): a second run waits, it never removes the first.
+	lk := tier2CopyLock(name)
+	lk.Lock()
+	defer lk.Unlock()
 	tier2CopyBegin(app)
 	defer tier2CopyEnd(app)
 	if tier2CappedPath(s) && tier2CappedPath(d) {
@@ -813,7 +823,9 @@ func rsyncMirror(src, dst string) error {
 				// created empty — an empty source would let `--delete` empty the copy (review 2026-10-22 night, C4).
 				"--mount", "type=bind,src=" + s + ",dst=" + s + ",readonly", "--mount", "type=bind,src=" + d + ",dst=" + d,
 				"--entrypoint", "rsync", img}, rs...)
+			tier2MarkRunning(name, true) // the start-up retry never removes a copy this process runs (review N3)
 			out, code, err := tier2RunCapped(ctx, args)
+			tier2MarkRunning(name, false)
 			if err == nil {
 				return nil
 			}

controller/internal/backup/tier2_copy_lifecycle.go

@@ -87,11 +87,39 @@ var tier2Docker = func(ctx context.Context, args ...string) ([]byte, error) {
 }
 
 // The controller's own record of copies (package-level: one controller, one backup manager per process).
+//   - inFlight: app → copies running now (capped or in-process);
+//   - running: the container names THIS process runs now — the start-up check never removes one of them;
+//   - strays: names whose removal failed — cleared when a later removal of that name works;
+//   - startupPending: the start-up check has not succeeded yet.
+//
+// Restores are refused while any of these is non-empty (review 2026-10-23 night, N2/N3: a stray used to block every
+// restore until a restart, and the start-up retry used to remove this process's own running copies).
 var tier2Copies = struct {
 	sync.Mutex
-	inFlight map[string]int // app → copies running now (capped or in-process)
-	stray    bool           // a container this process could not remove may still run, or the start-up removal has not succeeded
-}{inFlight: map[string]int{}}
+	inFlight       map[string]int
+	running        map[string]bool
+	strays         map[string]bool
+	startupPending bool
+	retrying       bool
+}{inFlight: map[string]int{}, running: map[string]bool{}, strays: map[string]bool{}}
+
+// tier2CopyLocks serializes copies into the SAME destination within this process (review N4): a second run waits for
+// the first instead of removing its container by name (which killed it mid-copy and mailed a false failure).
+var tier2CopyLocks = struct {
+	sync.Mutex
+	m map[string]*sync.Mutex
+}{m: map[string]*sync.Mutex{}}
+
+func tier2CopyLock(name string) *sync.Mutex {
+	tier2CopyLocks.Lock()
+	defer tier2CopyLocks.Unlock()
+	l := tier2CopyLocks.m[name]
+	if l == nil {
+		l = &sync.Mutex{}
+		tier2CopyLocks.m[name] = l
+	}
+	return l
+}
 
 func tier2CopyBegin(app string) {
 	tier2Copies.Lock()
@@ -107,55 +135,131 @@ func tier2CopyEnd(app string) {
 	tier2Copies.Unlock()
 }
 
-func tier2SetStray(v bool) {
+func tier2MarkRunning(name string, on bool) {
 	tier2Copies.Lock()
-	tier2Copies.stray = v
+	if on {
+		tier2Copies.running[name] = true
+	} else {
+		delete(tier2Copies.running, name)
+	}
 	tier2Copies.Unlock()
 }
 
 // tier2RemoveCopy removes the copy container `name` (no error when it does not exist). It reports whether the
-// container is surely gone; when not, the stray flag is set, so restores stay refused until a removal succeeds.
+// container is surely gone; when not, the name is recorded as a stray (restores refused) and retried every minute.
 func tier2RemoveCopy(name, why string) bool {
 	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
 	defer cancel()
 	out, err := tier2Docker(ctx, "rm", "-f", name)
 	if err != nil && !strings.Contains(strings.ToLower(string(out)), "no such container") {
-		tier2Logf("[ERROR] [tier2] could not remove the copy container %s (%s): %v %s — restores stay refused until it is removed",
+		tier2Logf("[ERROR] [tier2] could not remove the copy container %s (%s): %v %s — restores stay refused until it is removed (retried every minute)",
 			name, why, err, strings.TrimSpace(string(out)))
-		tier2SetStray(true)
+		tier2Copies.Lock()
+		tier2Copies.strays[name] = true
+		tier2Copies.Unlock()
+		tier2StartRetry(context.Background())
 		return false
 	}
+	tier2Copies.Lock()
+	delete(tier2Copies.strays, name)
+	tier2Copies.Unlock()
 	return true
 }
 
-// ClearLeftoverTier2Copies removes every labelled copy container — a copy a previous controller process started and
-// lost (restart, self-update, crash). It runs at controller start, BEFORE the scheduler and the web server; each
-// removal is logged. Until it succeeds, restores are refused; on failure it retries every minute in the background
-// until it succeeds or ctx ends.
-func ClearLeftoverTier2Copies(ctx context.Context) error {
-	tier2SetStray(true)
-	err := clearLeftoverTier2CopiesOnce(ctx)
-	if err == nil {
-		tier2SetStray(false)
-		return nil
+// tier2RetryEvery is the retry period for strays and a failed start-up check; tier2RetryOff (tests only) keeps the
+// background retry from starting at all — a timer that outlives a test would reach the real Docker of the host.
+var (
+	tier2RetryEvery = time.Minute
+	tier2RetryOff   = false
+)
+
+// tier2StartRetry starts ONE background retry (if none runs): every tier2RetryEvery it redoes a failed start-up check
+// and the removal of every stray, and ends when nothing is left or ctx ends.
+func tier2StartRetry(ctx context.Context) {
+	tier2Copies.Lock()
+	if tier2Copies.retrying || tier2RetryOff {
+		tier2Copies.Unlock()
+		return
 	}
-	tier2Logf("[ERROR] [tier2] the start-up check for a leftover second-drive copy failed: %v — restores are refused until it succeeds; retrying every minute", err)
+	tier2Copies.retrying = true
+	tier2Copies.Unlock()
+	every := tier2RetryEvery
 	go func() {
-		t := time.NewTicker(time.Minute)
+		t := time.NewTicker(every)
 		defer t.Stop()
 		for {
 			select {
 			case <-ctx.Done():
+				tier2Copies.Lock()
+				tier2Copies.retrying = false
+				tier2Copies.Unlock()
 				return
 			case <-t.C:
-				if clearLeftoverTier2CopiesOnce(ctx) == nil {
-					tier2SetStray(false)
-					tier2Logf("[INFO] [tier2] the leftover second-drive copy check succeeded — restores allowed again")
-					return
-				}
+			}
+			if tier2RetryOnce(ctx) {
+				tier2Logf("[INFO] [tier2] no leftover or stray second-drive copy container is left — restores allowed again")
+				return
 			}
 		}
 	}()
+}
+
+// tier2RetryOnce does one retry round; it reports (and clears `retrying`) when nothing is left to retry.
+func tier2RetryOnce(ctx context.Context) bool {
+	tier2Copies.Lock()
+	pending := tier2Copies.startupPending
+	var names []string
+	for n := range tier2Copies.strays {
+		names = append(names, n)
+	}
+	tier2Copies.Unlock()
+	if pending && clearLeftoverTier2CopiesOnce(ctx) == nil {
+		tier2Copies.Lock()
+		tier2Copies.startupPending = false
+		tier2Copies.Unlock()
+	}
+	for _, n := range names {
+		tier2RemoveCopyQuiet(ctx, n)
+	}
+	tier2Copies.Lock()
+	defer tier2Copies.Unlock()
+	if !tier2Copies.startupPending && len(tier2Copies.strays) == 0 {
+		tier2Copies.retrying = false
+		return true
+	}
+	return false
+}
+
+// tier2RemoveCopyQuiet is the retry's removal: a failure keeps the stray without starting another retry.
+func tier2RemoveCopyQuiet(ctx context.Context, name string) {
+	rctx, cancel := context.WithTimeout(ctx, 60*time.Second)
+	defer cancel()
+	out, err := tier2Docker(rctx, "rm", "-f", name)
+	if err != nil && !strings.Contains(strings.ToLower(string(out)), "no such container") {
+		return
+	}
+	tier2Copies.Lock()
+	delete(tier2Copies.strays, name)
+	tier2Copies.Unlock()
+	tier2Logf("[INFO] [tier2] the stray copy container %s is removed", name)
+}
+
+// ClearLeftoverTier2Copies removes every labelled copy container a previous controller process started and lost
+// (restart, self-update, crash). It runs at controller start, BEFORE the scheduler and the web server; each removal is
+// logged. Until it succeeds, restores are refused; on failure it is retried every minute in the background.
+func ClearLeftoverTier2Copies(ctx context.Context) error {
+	tier2Copies.Lock()
+	tier2Copies.startupPending = true
+	tier2Copies.Unlock()
+	err := clearLeftoverTier2CopiesOnce(ctx)
+	if err == nil {
+		tier2Copies.Lock()
+		tier2Copies.startupPending = false
+		tier2Copies.Unlock()
+		return nil
+	}
+	tier2Logf("[ERROR] [tier2] the start-up check for a leftover second-drive copy failed: %v — restores are refused until it succeeds; retrying every minute", err)
+	tier2StartRetry(ctx)
 	return err
 }
 
@@ -166,7 +270,14 @@ func clearLeftoverTier2CopiesOnce(ctx context.Context) error {
 	if err != nil {
 		return fmt.Errorf("docker ps: %v %s", err, strings.TrimSpace(string(out)))
 	}
-	names := strings.Fields(string(out))
+	var names []string
+	tier2Copies.Lock()
+	for _, n := range strings.Fields(string(out)) {
+		if !tier2Copies.running[n] { // never a copy THIS process runs (review N3)
+			names = append(names, n)
+		}
+	}
+	tier2Copies.Unlock()
 	if len(names) == 0 {
 		tier2Logf("[INFO] [tier2] start-up: no leftover second-drive copy container")
 		return nil
@@ -195,7 +306,7 @@ func clearLeftoverTier2CopiesOnce(ctx context.Context) error {
 func (m *Manager) Tier2CopyBlocksRestore() (app string, blocked bool) {
 	tier2Copies.Lock()
 	defer tier2Copies.Unlock()
-	if tier2Copies.stray {
+	if tier2Copies.startupPending || len(tier2Copies.strays) > 0 {
 		return "", true
 	}
 	for a := range tier2Copies.inFlight {
@@ -204,6 +315,14 @@ func (m *Manager) Tier2CopyBlocksRestore() (app string, blocked bool) {
 	return "", false
 }
 
+// tier2ResetForTest empties the record (tests only).
+func tier2ResetForTest() {
+	tier2Copies.Lock()
+	tier2Copies.inFlight, tier2Copies.running, tier2Copies.strays = map[string]int{}, map[string]bool{}, map[string]bool{}
+	tier2Copies.startupPending, tier2Copies.retrying = false, false
+	tier2Copies.Unlock()
+}
+
 // MarkTier2CopyForTest records a copy of app as running until the returned func is called — a test-only seam (another
 // package's test exercises the restore refusal without a real copy), in the spirit of AcquireRunningForTest.
 func MarkTier2CopyForTest(app string) func() {

controller/internal/backup/tier2_copy_lifecycle_test.go

@@ -33,7 +33,9 @@ func strayCopySeams(t *testing.T, root string, run func(ctx context.Context, arg
 	fn func(args []string) ([]byte, error)) (*dockerRec, *dockerRec) {
 	t.Helper()
 	runs, lifecycle := &dockerRec{}, &dockerRec{}
-	oldRoot, oldImg, oldRun, oldLog, oldDocker, oldTO := tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker, tier2CopyTimeout
+	oldRoot, oldImg, oldRun, oldLog, oldDocker, oldTO, oldRetry := tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker, tier2CopyTimeout, tier2RetryEvery
+	tier2RetryEvery = time.Hour
+	tier2RetryOff = true // the background retry never starts in a test (it would reach the real Docker later)
 	tier2CappedRoot = root
 	tier2SelfImage = func() string { return "sha256:abc" }
 	tier2RunCapped = func(ctx context.Context, args []string) ([]byte, int, error) {
@@ -49,10 +51,11 @@ func strayCopySeams(t *testing.T, root string, run func(ctx context.Context, arg
 		return fn(args)
 	}
 	tier2Logf = func(string, ...any) {}
-	tier2SetStray(false)
+	tier2ResetForTest()
 	t.Cleanup(func() {
-		tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker, tier2CopyTimeout = oldRoot, oldImg, oldRun, oldLog, oldDocker, oldTO
-		tier2SetStray(false)
+		tier2CappedRoot, tier2SelfImage, tier2RunCapped, tier2Logf, tier2Docker, tier2CopyTimeout, tier2RetryEvery = oldRoot, oldImg, oldRun, oldLog, oldDocker, oldTO, oldRetry
+		tier2RetryOff = false
+		tier2ResetForTest()
 	})
 	return runs, lifecycle
 }
@@ -210,3 +213,95 @@ func TestStrayCopy_ARestoreIsRefusedWhileACopyRuns(t *testing.T) {
 		t.Fatal("after the copy a restore must be allowed")
 	}
 }
+
+// Review 2026-10-23 night. N2: a stray clears when a later removal of that name works (it used to block every restore
+// until a restart). N3: the start-up check never removes a copy THIS process runs. N4: a second copy into the same
+// destination waits for the first instead of removing its container. RED-PROOF: with the stray delete on a successful
+// retry removed → StrayClears fails; with the `running` skip removed → OwnCopyKept fails; with the per-destination lock
+// removed → SameDestinationWaits fails — each seen failing 2026-10-23 night.
+func TestStrayCopy_AStrayClearsWhenALaterRemovalWorks(t *testing.T) {
+	root, src, dst := appDirs(t)
+	fail := true
+	strayCopySeams(t, root, func(context.Context, []string) ([]byte, int, error) { return nil, 0, nil },
+		func(args []string) ([]byte, error) {
+			if fail {
+				return []byte("Error response from daemon: cannot remove"), errors.New("exit 1")
+			}
+			return nil, nil
+		})
+	_ = rsyncMirror(src, dst)
+	if _, blocked := (&Manager{}).Tier2CopyBlocksRestore(); !blocked {
+		t.Fatal("fixture: an unremovable leftover must refuse restores")
+	}
+	fail = false
+	if !tier2RetryOnce(context.Background()) {
+		t.Fatal("the retry must report nothing left once the removal works")
+	}
+	if _, blocked := (&Manager{}).Tier2CopyBlocksRestore(); blocked {
+		t.Fatal("after the stray is removed, restores must be allowed again — without a controller restart")
+	}
+}
+
+func TestStrayCopy_TheStartUpCheckKeepsThisProcessesOwnCopy(t *testing.T) {
+	_, life := strayCopySeams(t, t.TempDir()+"/", nil, func(args []string) ([]byte, error) {
+		if args[0] == "ps" {
+			return []byte("felhom-tier2-copy-mine-00000001\nfelhom-tier2-copy-old-00000002\n"), nil
+		}
+		return nil, nil
+	})
+	tier2MarkRunning("felhom-tier2-copy-mine-00000001", true)
+	if err := clearLeftoverTier2CopiesOnce(context.Background()); err != nil {
+		t.Fatal(err)
+	}
+	got := life.all()
+	if strings.Contains(got, "rm -f felhom-tier2-copy-mine-00000001") || !strings.Contains(got, "rm -f felhom-tier2-copy-old-00000002") {
+		t.Fatalf("the check must remove only the leftover, never this process's running copy:\n%s", got)
+	}
+}
+
+func TestStrayCopy_ASecondCopyOfTheSameDestinationWaits(t *testing.T) {
+	root, src, dst := appDirs(t)
+	var mu sync.Mutex
+	order := []string{}
+	release := make(chan struct{})
+	first := true
+	runs, _ := strayCopySeams(t, root, func(context.Context, []string) ([]byte, int, error) {
+		mu.Lock()
+		me := first
+		first = false
+		order = append(order, "start")
+		mu.Unlock()
+		if me {
+			<-release
+		}
+		mu.Lock()
+		order = append(order, "end")
+		mu.Unlock()
+		return nil, 0, nil
+	}, func(args []string) ([]byte, error) {
+		mu.Lock()
+		order = append(order, strings.Join(args, " "))
+		mu.Unlock()
+		return nil, nil
+	})
+	d1, d2 := make(chan error), make(chan error)
+	go func() { d1 <- rsyncMirror(src, dst) }()
+	for len(strings.Split(runs.all(), "\n")) < 1 || runs.all() == "" {
+		time.Sleep(5 * time.Millisecond)
+	}
+	go func() { d2 <- rsyncMirror(src, dst) }()
+	time.Sleep(100 * time.Millisecond)
+	mu.Lock()
+	during := strings.Join(order, "|")
+	mu.Unlock()
+	if strings.Count(during, "rm -f") != 1 {
+		t.Fatalf("while the first copy runs, the second must not touch its container: %s", during)
+	}
+	close(release)
+	if err := <-d1; err != nil {
+		t.Fatal(err)
+	}
+	if err := <-d2; err != nil {
+		t.Fatal(err)
+	}
+}