basefilectx: move __str__ from filectx

mercurial/context.py

@@ -455,6 +455,9 b' class basefilectx(object):'
             # file is missing
             return False
 
+    def __str__(self):
+        return "%s@%s" % (self.path(), short(self.node()))
+
 class filectx(basefilectx):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
@@ -504,9 +507,6 b' class filectx(basefilectx):'
             # considered when solving linkrev issue are on the table.
             return changectx(self._repo.unfiltered(), self._changeid)
 
-    def __str__(self):
-        return "%s@%s" % (self.path(), short(self.node()))
-
     def __repr__(self):
         return "<filectx %s>" % str(self)