Index: tracext/hg/backend.py
===================================================================
--- tracext/hg/backend.py	(revision 9983)
+++ tracext/hg/backend.py	(working copy)
@@ -277,7 +277,7 @@
         options.update(params)
         if not self.ui:
             self._setup_ui(options.get('hgrc'))
-        repos = MercurialRepository(dir, options, self.log, self.ui)
+        repos = MercurialRepository(dir, options, self.log, self.ui, self._version)
         repos.version_info = self._version_info
         return repos
 
@@ -361,7 +361,7 @@
     additional changeset properties.
     """
 
-    def __init__(self, path, params, log, ui):
+    def __init__(self, path, params, log, ui, version):
         self.ui = ui
         # TODO: per repository ui and options?
         if isinstance(path, unicode):
@@ -374,6 +374,7 @@
             self.path = self.repo.root
         except RepoError, e:
             self.path = None
+            log.error('[hg] mercurial %s can\'t read %s repository: %s' % (version, path, e))
         self._show_rev = True
         if 'show_rev' in params and not params['show_rev'] in TRUE:
             self._show_rev = False