convert: move svn config initializer out of the module level

The svn_config_get_config config call was being called at the module level, but
had the potential to throw permission denied errors if ~/.subversion/servers was
not readable. This could happen in certain test environments where the user
permissions were very particular.

This prevented the remotenames extension from loading, since it imports
convert's hg module, which imports convert's subversion module, which calls
this. The config is only ever used from this one constructor, so let's just move
it in to there.

hgext/convert/transport.py

@@ -34,8 +34,7 b' from mercurial import ('
 # won't work worth a darn against those libraries anyway!
 svn.ra.initialize()
 
-svn_config = svn.core.svn_config_get_config(None)
-
+svn_config = None
 
 def _create_auth_baton(pool):
     """Create a Subversion authentication baton. """
@@ -88,6 +87,9 b' class SvnRaTransport(object):'
                 svn.core.svn_auth_set_parameter(
                     ab, svn.core.SVN_AUTH_PARAM_DEFAULT_PASSWORD, self.password)
             self.client.auth_baton = ab
+            global svn_config
+            if svn_config is None:
+                svn_config = svn.core.svn_config_get_config(None)
             self.client.config = svn_config
             try:
                 self.ra = svn.client.open_ra_session(