The sound plugin of gnome-settings-daemon which flushes the pulseaudio
sample cache does non-recursive monitoring of the sounds directory. If
the custom theme directory used for switching between bell sounds
already exists due to previous bell sound changes, subsequent changes
within that directory will not be noticed. The old bell sample will thus
remain in the cache until the next session restart. Avoid this problem
by manually updating the modification time of the directory.
The alternative solution of adding recursive monitoring to the sound
plugin would require significantly more complicated code as there is no
support for this in glib itself. Given that sound themes never really
caught on and there is an ongoing discussion of removing support for
them entirely, going with this simple solution seems like the better
choice.
Fixes: https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/issues/681
