diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -2291,10 +2291,7 @@
     # If we're doing a partial update, we need to skip updating
     # the dirstate, so make a note of any partial-ness to the
     # update here.
-    if matcher is None or matcher.always():
-        partial = False
-    else:
-        partial = True
+    always = matcher is None or matcher.always()
     with repo.wlock():
         if wc is None:
             wc = repo[None]
@@ -2507,7 +2504,7 @@
         ### apply phase
         if not branchmerge:  # just jump to the new rev
             fp1, fp2, xp1, xp2 = fp2, nullid, xp2, b''
-        updatedirstate = not partial and not wc.isinmemory()
+        updatedirstate = 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