=== the collision, three overlap offsets: full restore FIRST, then the check into it ===
--- restore, then check +1s ---
t_restore=08:24:09
[http=302 wall=0.010349s]
t_check=08:24:10
"duration_ms":0 "ok":false "skip_reason":"a backup or restore is already running" "skipped":true "ok":true 
--- restore, then check +2s ---
t_restore=08:24:22
[http=302 wall=0.010791s]
t_check=08:24:24
"duration_ms":39978 "ok":true "skip_reason":"" "skipped":false "ok":true 
--- restore, then check +3s ---
t_restore=08:25:19
[http=302 wall=0.011009s]
t_check=08:25:22
"duration_ms":0 "ok":false "skip_reason":"a backup or restore is already running" "skipped":true "ok":true 

=== THE NON-EFFECT: unlock --remove-all must appear in NO argv ===
  'unlock --remove-all' in the sampler: 0
  any 'unlock' at all:                  0
  'cleared a stale exclusive lock' in the log: 0

=== and the check SKIPPED rather than colliding ===
integrity: check PASSED in 1m4s (structure, index, and 100% of the pack data re-read)
integrity: skipped — a backup or restore is already running; due-ness is NOT advanced, so this retries on the next run
off-box restore refused for kimai (mode=full): another backup/restore op is already running
off-box restore kimai completed (full=true, async)
integrity: check PASSED in 40s (structure, index, and 100% of the pack data re-read)
integrity: skipped — a backup or restore is already running; due-ness is NOT advanced, so this retries on the next run
off-box restore kimai completed (full=true, async)