diff --git a/mercurial/shelve.py b/mercurial/shelve.py
--- a/mercurial/shelve.py
+++ b/mercurial/shelve.py
@@ -42,7 +42,6 @@
     lock as lockmod,
     mdiff,
     merge,
-    mergestate as mergestatemod,
     node as nodemod,
     patch,
     phases,
@@ -802,7 +801,7 @@
     basename = state.name
     with repo.lock():
         checkparents(repo, state)
-        ms = mergestatemod.mergestate.read(repo)
+        ms = repo[None].mergestate()
         if list(ms.unresolved()):
             raise error.Abort(
                 _(b"unresolved conflicts, can't continue"),