As per this mailing list question.
We have to stop the pulseaudio server using "pactl exit" to ensure it does not get restarted.
Should be fixed in r9620. Needs backporting.
I don't like execing something that always returns 0 whether it succeeded in doing what we asked for or not... but that's the only way that reliably stops the pulseaudio server on Ubuntu.
Backports in r9621. Tested on Fedora and Ubuntu, closing.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/889