diff --git a/hgext/fix.py b/hgext/fix.py
--- a/hgext/fix.py
+++ b/hgext/fix.py
@@ -735,15 +735,7 @@
 
     wctx = context.overlayworkingctx(repo)
     wctx.setbase(repo[newp1node])
-    merge.update(
-        repo,
-        ctx.rev(),
-        branchmerge=False,
-        force=True,
-        ancestor=p1rev,
-        mergeancestor=False,
-        wc=wctx,
-    )
+    merge.revert_to(ctx, wc=wctx)
     copies.graftcopies(wctx, ctx, ctx.p1())
 
     for path in filedata.keys():
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -584,15 +584,8 @@
             [os.unlink(repo.wjoin(c)) for c in newlyaddedandmodifiedfiles]
             # 3a. apply filtered patch to clean repo  (clean)
             if backups:
-                # Equivalent to hg.revert
                 m = scmutil.matchfiles(repo, set(backups.keys()) | alsorestore)
-                mergemod.update(
-                    repo,
-                    repo.dirstate.p1(),
-                    branchmerge=False,
-                    force=True,
-                    matcher=m,
-                )
+                mergemod.revert_to(repo[b'.'], matcher=m)
 
             # 3b. (apply)
             if dopatch:
diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -2205,6 +2205,7 @@
     labels=None,
     matcher=None,
     mergeforce=False,
+    updatedirstate=True,
     updatecheck=None,
     wc=None,
 ):
@@ -2504,7 +2505,7 @@
         ### apply phase
         if not branchmerge:  # just jump to the new rev
             fp1, fp2, xp1, xp2 = fp2, nullid, xp2, b''
-        updatedirstate = always and not wc.isinmemory()
+        updatedirstate = updatedirstate and always and not wc.isinmemory()
         if updatedirstate:
             repo.hook(b'preupdate', throw=True, parent1=xp1, parent2=xp2)
             # note that we're in the middle of an update
@@ -2578,6 +2579,18 @@
     return stats
 
 
+def revert_to(ctx, matcher=None, wc=None):
+    return update(
+        ctx.repo(),
+        ctx.rev(),
+        branchmerge=False,
+        force=True,
+        updatedirstate=False,
+        matcher=matcher,
+        wc=wc,
+    )
+
+
 def graft(
     repo, ctx, base, labels=None, keepparent=False, keepconflictparent=False
 ):