--- a/hgext/mq.py	Sun Sep 11 12:20:39 2011 +0100
+++ b/hgext/mq.py	Sun Sep 11 18:49:38 2011 +0200
@@ -626,6 +626,7 @@
             self.ui.note(str(inst) + '\n')
             if not self.ui.verbose:
                 self.ui.warn(_("patch failed, unable to continue (try -v)\n"))
+            self.ui.traceback()
             return (False, list(files), False)
 
     def apply(self, repo, series, list=False, update_status=True,