Bug#792524: same crash again

[Daniel Pocock]

I've observed the same crash again but this time it was not preceded by
any message from gnome-session/gnome-shell/mutter in the log

Looking through the logs, I found the same message has been occurring
intermittently at different times, even when the machine didn't crash,
therefore, I would suggest keeping this bug open but lowering the
severity and changing the bug title to focus on what this message means

gnome-session[2616]: (gnome-shell:2782): mutter-CRITICAL **:
meta_window_focus: assertion '!window->override_redirect' failed