In /etc/X11/xdm/Xsession, the variable $XKB_IN_USE in tests at lines 55
and 66 should
be enclosed in double quotes. Have hit cases where value is null,
syntactic error in script. Sorry, cannot read portion of my note about
caused the variable to have null value.
*** Bug 17711 has been marked as a duplicate of this bug. ***
Fixed in rawhide (not sure when as I just found it). ;o)
This is part of the xinitrc package.