diff --git a/kallithea/controllers/pullrequests.py b/kallithea/controllers/pullrequests.py
--- a/kallithea/controllers/pullrequests.py
+++ b/kallithea/controllers/pullrequests.py
@@ -578,17 +578,17 @@ class PullrequestsController(BaseRepoCon
         if org_scm_instance.alias == 'hg' and c.a_ref_name != 'ancestor':
             if c.cs_ref_type != 'branch':
                 c.cs_branch_name = org_scm_instance.get_changeset(c.cs_ref_name).branch # use ref_type ?
-            other_branch_name = c.a_ref_name
+            c.a_branch_name = c.a_ref_name
             if c.a_ref_type != 'branch':
                 try:
-                    other_branch_name = other_scm_instance.get_changeset(c.a_ref_name).branch # use ref_type ?
+                    c.a_branch_name = other_scm_instance.get_changeset(c.a_ref_name).branch # use ref_type ?
                 except EmptyRepositoryError:
-                    other_branch_name = 'null' # not a branch name ... but close enough
+                    c.a_branch_name = 'null' # not a branch name ... but close enough
             # candidates: descendants of old head that are on the right branch
             #             and not are the old head itself ...
             #             and nothing at all if old head is a descendent of target ref name
-            if other_scm_instance._repo.revs('present(%s)::&%s', c.cs_ranges[-1].raw_id, other_branch_name):
-                c.update_msg = _('This pull request has already been merged to %s.') % other_branch_name
+            if other_scm_instance._repo.revs('present(%s)::&%s', c.cs_ranges[-1].raw_id, c.a_branch_name):
+                c.update_msg = _('This pull request has already been merged to %s.') % c.a_branch_name
             else: # look for children of PR head on source branch in org repo
                 arevs = org_scm_instance._repo.revs('%s:: & branch(%s) - %s',
                                                     revs[0], c.cs_branch_name, revs[0])