mercurial/discovery.py

--- a/mercurial/discovery.py	Fri Oct 09 15:37:05 2015 -0700
+++ b/mercurial/discovery.py	Fri Oct 09 15:44:00 2015 -0700
@@ -320,6 +320,9 @@
             #
             # These two cases will be easy to handle for known changeset but
             # much more tricky for unsynced changes.
+            #
+            # In addition, this code is confused by prune as it only looks for
+            # successors of the heads (none if pruned) leading to issue4354
             newhs = set()
             for nh in candidate_newhs:
                 if nh in repo and repo[nh].phase() <= phases.public: