basefilectx: move __repr__ from filectx

We change the hardcoded 'filectx' to instead use type(self).__name__ so that objects that
inherit from basefilectx in the future will be able to use the same representation.

mercurial/context.py

@@ -458,6 +458,9 b' class basefilectx(object):'
     def __str__(self):
         return "%s@%s" % (self.path(), short(self.node()))
 
+    def __repr__(self):
+        return "<%s %s>" % (type(self).__name__, str(self))
+
 class filectx(basefilectx):
     """A filecontext object makes access to data related to a particular
        filerevision convenient."""
@@ -507,9 +510,6 b' class filectx(basefilectx):'
             # considered when solving linkrev issue are on the table.
             return changectx(self._repo.unfiltered(), self._changeid)
 
-    def __repr__(self):
-        return "<filectx %s>" % str(self)
-
     def __hash__(self):
         try:
             return hash((self._path, self._filenode))