commitablectx: move __str__ from workingctx

mercurial/context.py

@@ -856,6 +856,9 b' class commitablectx(basectx):'
         if self._extra['branch'] == '':
             self._extra['branch'] = 'default'
 
+    def __str__(self):
+        return str(self._parents[0]) + "+"
+
 class workingctx(commitablectx):
     """A workingctx object makes access to data related to
     the current working directory convenient.
@@ -869,9 +872,6 b' class workingctx(commitablectx):'
                  changes=None):
         super(workingctx, self).__init__(repo, text, user, date, extra, changes)
 
-    def __str__(self):
-        return str(self._parents[0]) + "+"
-
     def __nonzero__(self):
         return True