Add it second place, so it goes after '.' but before the normal path. This
allows per-directory config files (desirable for multiple darcsweb
installations on the same machin), and avoids name clashing if there's a
config.py in the standard path.
This was reported by Philipp Kern <pkern@debian.org> in Debian bug 399751
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=399751).