Dear Maintainer,

steps to reproduce:
* play a recording (foo)
* set some cut marks (so that the resulting recording needs some time to be written to)
* cut
* play cut resulting recording (%foo) while being written to
* delete (%foo)

results:
* osd hangs
* vdr exits after a while and gets restarted by systemd
* gaps in recordings currently recorded from sat

expected results:
* cutting is aborted
* playback is stopped
* recording (%foo) deleted

excerpts from syslog:
Dec 25 16:41:26 klotze vdr: [1393] loading /var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec/marks
Dec 25 16:41:26 klotze vdr: [1393] recordings handler add 4 '/var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec' '(null
)'
Dec 25 16:41:26 klotze vdr: [1393] loading /var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec/marks
Dec 25 16:41:26 klotze vdr: [1393] info: Schnitt gestartet
Dec 25 16:41:26 klotze vdr: [11655] recordings handler thread started (pid=1393, tid=11655, prio=high)
Dec 25 16:41:26 klotze vdr: [11655] loading /var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec/marks
Dec 25 16:41:26 klotze vdr: [11655] executing '/usr/lib/vdr/vdr-recordingaction editing "/var/lib/video/%Wenn_wir_uns_begegnen/201
9-12-22.14.16.1-0.rec" "/var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec"'
Dec 25 16:41:26 klotze recordingaction: executing shell script /usr/share/vdr/recording-hooks/R90.custom editing /var/lib/video/%W
enn_wir_uns_begegnen/2019-12-22.14.16.1-0.rec /var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec
Dec 25 16:41:26 klotze vdr[1393]: /usr/share/vdr/recording-hooks/R90.custom: 25: /usr/share/vdr/recording-hooks/R90.custom: ,: not
 found
Dec 25 16:41:26 klotze vdr: [11655] creating directory /var/lib/video/%Wenn_wir_uns_begegnen/2019-12-22.14.16.1-0.rec
Dec 25 16:41:26 klotze vdr: [11655] loading /var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec/marks
Dec 25 16:41:26 klotze vdr: [11655] playing '/var/lib/video/Wenn_wir_uns_begegnen/2019-12-22.14.15.1-0.rec/00001.ts'
Dec 25 16:41:26 klotze vdr: [11655] recording to '/var/lib/video/%Wenn_wir_uns_begegnen/2019-12-22.14.16.1-0.rec/00001.ts'
Dec 25 16:41:26 klotze vdr: [11663] video cutting thread started (pid=1393, tid=11663, prio=low)
Dec 25 16:41:31 klotze vdr: [11650] non blocking file reader thread ended (pid=1393, tid=11650)
Dec 25 16:41:31 klotze vdr: [11649] dvbplayer thread ended (pid=1393, tid=11649)
Dec 25 16:41:31 klotze vdr: [1393] replay /var/lib/video/%Wenn_wir_uns_begegnen/2019-12-22.14.16.1-0.rec
Dec 25 16:41:31 klotze vdr: [1393] playing '/var/lib/video/%Wenn_wir_uns_begegnen/2019-12-22.14.16.1-0.rec/00001.ts'
Dec 25 16:41:31 klotze vdr: [11664] dvbplayer thread started (pid=1393, tid=11664, prio=high)
Dec 25 16:41:31 klotze vdr: [11665] non blocking file reader thread started (pid=1393, tid=11665, prio=high)
Dec 25 16:41:41 klotze vdr: [1393] confirm: Aufzeichnung löschen?
Dec 25 16:41:41 klotze vdr: [1393] warning: Aufzeichnung löschen?
Dec 25 16:41:41 klotze vdr: [1393] confirmed
Dec 25 16:41:41 klotze vdr: [1393] confirm: Aufzeichnung wird bearbeitet - trotzdem löschen?
Dec 25 16:41:41 klotze vdr: [1393] warning: Aufzeichnung wird bearbeitet - trotzdem löschen?
Dec 25 16:41:42 klotze vdr: [1393] confirmed
Dec 25 16:41:42 klotze vdr: [11663] video cutting thread ended (pid=1393, tid=11663)
Dec 25 16:41:42 klotze vdr: [11655] editing process has been interrupted
Dec 25 16:42:40 klotze vdr: [1393] PANIC: watchdog timer expired - exiting!
Dec 25 16:42:43 klotze vdr[1393]: exception occured: pthread_mutex_lock failed: errno 22: Das Argument ist ungültig
Dec 25 16:42:43 klotze vdr: [1393] ERROR: ListGarbageCollector destroyed without prior Purge()!
Dec 25 16:42:43 klotze vdr: [11618] osdteletext-receiver thread ended (pid=1393, tid=11618)
Dec 25 16:42:43 klotze vdr: [1393] buffer stats: 0 (0%) used
Dec 25 16:42:43 klotze lircd-0.10.1[860]: Info: removed client
Dec 25 16:42:43 klotze lircd[860]: lircd-0.10.1[860]: Info: removed client
Dec 25 16:42:46 klotze vdr: [1393] ERROR: recordings handler thread 11655 won't end (waited 3 seconds) - canceling it...
Dec 25 16:42:46 klotze systemd[1]: vdr.service: Main process exited, code=exited, status=1/FAILURE