diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -2956,6 +2956,7 @@
                 or self.ui.configbool(b'ui', b'allowemptycommit')
             )
             if not allowemptycommit:
+                self.ui.debug(b'nothing to commit, clearing merge state\n')
                 ms.reset()
                 return None
 
diff --git a/tests/test-graft.t b/tests/test-graft.t
--- a/tests/test-graft.t
+++ b/tests/test-graft.t
@@ -758,6 +758,7 @@
    branchmerge: True, force: True, partial: False
    ancestor: b592ea63bb0c, local: 7e61b508e709+, remote: 7a4785234d87
   starting 4 threads for background file closing (?)
+  nothing to commit, clearing merge state
   note: graft of 13:7a4785234d87 created no changes to commit
   $ hg log -r 'destination(13)'
 All copies of a cset