--- a/hgext/rebase.py	Tue Jun 23 22:38:21 2015 -0700
+++ b/hgext/rebase.py	Tue Jun 23 22:20:08 2015 -0700
@@ -838,7 +838,7 @@
         _setrebasesetvisibility(repo, state.keys())
         return (originalwd, target, state, skipped,
                 collapse, keep, keepbranches, external, activebookmark)
-    except IOError, err:
+    except IOError as err:
         if err.errno != errno.ENOENT:
             raise
         raise util.Abort(_('no rebase in progress'))