This is solely used for filtering by unittest, however, if it is
missing, then unittest will fail. So generate a reasonable name (which
is unfortunately not identical to the real name of the attribute).
Python isn't always installed in /usr/bin. If we hard-code the path,
these tests will fail on *BSD because they install python in different
prefixes such as /usr/local and /usr/pkg.
This makes running glib based tests inside a dbusmock environment easier
and more beautiful (i.e. output is supressed unless an error occurs).
This helper has been submitted for inclusion in dbusmock. If it cannot$
live there in some form, then we should try to find a home in the GNOME$
project for it.$
