--- a/hgext/rebase.py	Thu Jan 09 15:41:40 2020 -0800
+++ b/hgext/rebase.py	Fri Jan 10 17:03:23 2020 -0800
@@ -1430,7 +1430,7 @@
 
     # By convention, ``extra['branch']`` (set by extrafn) clobbers
     # ``branch`` (used when passing ``--keepbranches``).
-    branch = repo[p1].branch()
+    branch = None
     if b'branch' in extra:
         branch = extra[b'branch']