diff -r e23c03dc5cf9 -r 4b816a83e17e mercurial/repository.py
--- a/mercurial/repository.py	Mon Sep 24 09:59:19 2018 -0700
+++ b/mercurial/repository.py	Mon Sep 24 10:08:58 2018 -0700
@@ -741,13 +741,6 @@
 class ifilestorage(ifileindex, ifiledata, ifilemutation):
     """Complete storage interface for a single tracked file."""
 
-    _generaldelta = interfaceutil.Attribute(
-        """Whether deltas can be against any parent revision.
-
-        TODO this is used by changegroup code and it could probably be
-        folded into another API.
-        """)
-
     def files():
         """Obtain paths that are backing storage for this file.