--- a/hgext/rebase.py	Wed Feb 03 09:24:47 2016 -0800
+++ b/hgext/rebase.py	Wed Feb 03 09:23:31 2016 -0800
@@ -621,10 +621,7 @@
         if commitmsg is None:
             commitmsg = ctx.description()
         keepbranch = keepbranches and repo[p1].branch() != ctx.branch()
-        extra = ctx.extra().copy()
-        if not keepbranches:
-            del extra['branch']
-        extra['rebase_source'] = ctx.hex()
+        extra = {'rebase_source': ctx.hex()}
         if extrafn:
             extrafn(ctx, extra)