Bug#636135: Confirmed, modesetting-specific
tags 636135 + confirmed
Human memory is so weak. After working around this in my previous
install, I had already completely forgotten about the bug and just spent
about an hour debugging it...
Re-applying the workaround worked, however the new kdmrc is very
different and doesn't contain TerminateServer anymore, so I had to
proceed as others said, adding "TerminateServer=true" in the [X-:*-Core]
section (line 59).
I noticed that this only happens with modesetting. The problem does not
happen when Linux is booted with radeon.modeset=0.