--- a/hgext/rebase.py	Thu Jan 20 11:06:52 2022 -0800
+++ b/hgext/rebase.py	Tue Jan 18 14:57:15 2022 -0800
@@ -1544,7 +1544,7 @@
         force=True,
         ancestor=base,
         mergeancestor=mergeancestor,
-        labels=[b'dest', b'source'],
+        labels=[b'dest', b'source', b'parent of source'],
         wc=wctx,
     )
     wctx.setparents(p1ctx.node(), repo[p2].node())