test-strip: fix call to super class in crashstriprepo

The 'self' argument is already taken care of by the 'super(...)' call. Instead
we were passing the repository instance as the 'desc' value.

This got discovered by breaking the next changeset.

tests/test-strip.t

@@ -928,7 +928,7 b' Error during post-close callback of the '
   > def reposetup(ui, repo):
   >     class crashstriprepo(repo.__class__):
   >         def transaction(self, desc, *args, **kwargs):
-  >             tr = super(crashstriprepo, self).transaction(self, desc, *args, **kwargs)
+  >             tr = super(crashstriprepo, self).transaction(desc, *args, **kwargs)
   >             if desc == 'strip':
   >                 def crash(tra): raise error.Abort('boom')
   >                 tr.addpostclose('crash', crash)