4.0 regression: test_libvlc_slaves fails pseudorandomly

FAIL: test_libvlc_slaves
========================

[000060e000000040] main libvlc warning: cannot read /home/remi/videolan/vlc/build/src/.libs/vlc/plugins/plugins.dat: No such file or directory
[000060e000001380] main libvlc warning: cannot read /home/remi/videolan/vlc/build/src/.libs/vlc/plugins/plugins.dat: No such file or directory
LibVLC fatal error joining thread (35) in thread 175333 at ../../src/posix/thread.c:227 in vlc_join
/usr/lib/x86_64-linux-gnu/libasan.so.6(+0x43df1)[0x7fcb7cd60df1]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x94b611)[0x7fcb7bba2611]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x94b773)[0x7fcb7bba2773]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(vlc_join+0x11c)[0x7fcb7bba3085]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(vlc_executor_Delete+0x438)[0x7fcb7bb0557a]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x62de7a)[0x7fcb7b884e7a]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(libvlc_InternalCleanup+0x5ba)[0x7fcb7b7d6c68]
/home/remi/videolan/vlc/build/lib/.libs/libvlc.so.12(libvlc_release+0x122)[0x7fcb7b183e57]
/home/remi/videolan/vlc/build/lib/.libs/libvlc.so.12(libvlc_media_release+0x63f)[0x7fcb7b19b940]
/home/remi/videolan/vlc/build/lib/.libs/libvlc.so.12(+0x8006a)[0x7fcb7b19a06a]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x62990a)[0x7fcb7b88090a]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x62bbb7)[0x7fcb7b882bb7]
/home/remi/videolan/vlc/build/src/.libs/libvlccore.so.9(+0x8acabf)[0x7fcb7bb03abf]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x8ea7)[0x7fcb7af33ea7]
/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f)[0x7fcb7b052d4f]

## Testing --sub-autodetect-fuzzy 1 (everything)
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/test.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media
Check if slaves[0] is found
Check if slaves[1] is found
Check if slaves[2] is found
Check if slaves[3] is found

## Testing --sub-autodetect-fuzzy 2 (full, left, and right match)
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/test.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media
Check if slaves[0] is found
Check if slaves[1] is found
Check if slaves[2] is found

## Testing if the matching is not too permissive
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/t.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media

## Testing --sub-autodetect-fuzzy 3 (full and left match)
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/test.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media
Check if slaves[0] is found
Check if slaves[1] is found

## Testing --sub-autodetect-fuzzy 4 (full match)
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/test.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media
Check if slaves[0] is found

## Testing  --no-sub-autodetect-file (no match)
Parse media dir to get subitems
Main media mrl: 'file:///home/remi/videolan/vlc/build/test/../../test/samples/slaves/test.mp4'
Fetch main media from subitems
Found main media
Check if slaves are correclty attached to media
Thread error: Success
FAIL test_libvlc_slaves (exit status: 134)

Bisection not done as failure is intermittent. Looking at the stack trace, this is most likely caused by the migratiom of something onto the executor API.