Bug#526839: Gnome-session update causes this

[Terry Watt]

This bug appears when gnome-session is updated to 2.22.3-3, and only 
after logging out/back in.  I isolated the problem to the new 
/etc/X11/Xsession.d/55gnome-session_gnomerc; restoring the old 
55gnome-session_gnomerc from 2.22.3-2 alone is enough to restore Yelp 
(after logout).

Specially, the problem seems to be something in the added path information:
>   # We prepend /usr/share/gnome since it actually points to /etc so
>   # it is configurable.
>   if [ -z "$XDG_DATA_DIRS" ]; then
>     XDG_DATA_DIRS=/usr/share/gnome:/usr/local/share/:/usr/share/
>   else
>     XDG_DATA_DIRS=/usr/share/gnome:"$XDG_DATA_DIRS"
>   fi
>   export XDG_DATA_DIRS
> fi
Since my /usr/share/gnome does not point to /etc, I assume that has 
something to do with the problem.