diff -r d4e715d2be0b -r 2c2788ce0257 mercurial/mergestate.py
--- a/mercurial/mergestate.py	Thu Sep 30 18:00:39 2021 +0200
+++ b/mercurial/mergestate.py	Fri Oct 01 00:00:29 2021 +0200
@@ -821,8 +821,15 @@
         if branchmerge:
             # We've done a branch merge, mark this file as merged
             # so that we properly record the merger later
+            p1_tracked = f1 == f
+            p2_tracked = f2 == f
             repo.dirstate.update_file(
-                f, p1_tracked=True, wc_tracked=True, merged=True
+                f,
+                p1_tracked=p1_tracked,
+                p2_tracked=p2_tracked,
+                wc_tracked=True,
+                merged=p1_tracked,
+                clean_p2=not p1_tracked,
             )
             if f1 != f2:  # copy/rename
                 if move: