mercurial/copies.py

--- a/mercurial/copies.py	Tue Jul 23 12:03:24 2019 +0530
+++ b/mercurial/copies.py	Mon Jul 22 17:44:19 2019 -0700
@@ -246,7 +246,7 @@
     return cm
 
 def _changesetforwardcopies(a, b, match):
-    if a.rev() == node.nullrev:
+    if a.rev() in (node.nullrev, b.rev()):
         return {}
 
     repo = a.repo()