Bug#196726: xserver-xfree86 4.2.1-7 doesn't allow clients to connect

[Jeff King <peff-debbug@peff.net>]

I did some more playing with combinations of package versions, and
here's what I found:

all packages at 4.2.1-7: broken
all packages at 4.2.1-6: works
xserver-xfree86 at 4.2.1-7, rest at 4.2.1-6: broken
xlibs at 4.2.1-7, rest at 4.2.1-6: broken
xserver-xfree86 and xlibs at 4.2.1-6, rest at 4.2.1-7: works

So it breaks if either xserver-xfree86 or xlibs is upgraded, but it
doesn't seem to matter for the rest of the X packages. Which leads me to
conclude:
 - this is not necessarily an xserver-xfree86 bug, and should
   potentially be reclassified
 - xdm can still connect in the new version; this is presumably because
   the auth code is statically linked into xdm itself. However, when it
   calls external programs (like xconsole or xrdb), they can't connect
   (since they're using xlibs). So it seems like there is something
   funny in xlibs, but the same something is *not* broken in xdm.
   I also don't know too much about how xdm does its authentication.
   Should it potentially be calling xauth or something to add the
   MIT-MAGIC-COOKIE-1 token?

-Peff