arb_launcher fails to terminate w/o error state

[westram]

Example:

ARB: ARB: Loading '/testdir/example.arb'
ARB: ARB: no FastLoad File '/testdir/example.ARM' found => loading entire DB
ARB: ARB: Loading '/testdir/example.arb' done

[arb_launcher[0]: 'arb_ntree /testdir/example.arb' has terminated with success]
[arb_launcher[0]: All launched processes terminated]
[arb_launcher[0]: cleaning up arb session]
  PID TTY      STAT   TIME COMMAND
rmdir: failed to remove `/home/theuser/.arb_prop/logs/20191118_135331.441': Directory not empty

Session log has been stored in /home/theuser/.arb_prop/logs/session.20191118_135331.441.tgz
    and is also accessible via /home/theuser/ARB_last_session.tgz
me@here> ll /home/theuser/.arb_prop/logs/20191118_135331.441
total 29
drwxr-xr-x 2 theuser grp   3 2019-11-18 13:54 .
drwxr-x--- 4 theuser grp   6 2019-11-18 13:54 ..
-rw-r--r-- 1 theuser grp 179 2019-11-18 13:54 server.log
me@here> cat /home/theuser/.arb_prop/logs/20191118_135331.441/server.log
Mon Nov 18 13:53:31 CET 2019 arb server.log created by arb_launcher
Mon Nov 18 13:54:39 CET 2019 arb_launcher terminates now. leftover servers may continue logging into this file
me@here>

Reason:

• server.log is not removed
• probably this is done intentionally (because servers may continue to write there)

Solution:

• do not delete log directories at arb shutdown
• instead cleanup "older" log directories on startup