diff -r b74e128676d4 -r 5105a9975407 hgext/extdiff.py
--- a/hgext/extdiff.py	Tue Sep 28 13:59:01 2021 -0700
+++ b/hgext/extdiff.py	Tue Sep 28 15:11:22 2021 -0700
@@ -559,15 +559,15 @@
     do3way = b'$parent2' in cmdline
 
     if change:
-        ctx2 = scmutil.revsingle(repo, change, None)
+        ctx2 = logcmdutil.revsingle(repo, change, None)
         ctx1a, ctx1b = ctx2.p1(), ctx2.p2()
     elif from_rev or to_rev:
         repo = scmutil.unhidehashlikerevs(
             repo, [from_rev] + [to_rev], b'nowarn'
         )
-        ctx1a = scmutil.revsingle(repo, from_rev, None)
+        ctx1a = logcmdutil.revsingle(repo, from_rev, None)
         ctx1b = repo[nullrev]
-        ctx2 = scmutil.revsingle(repo, to_rev, None)
+        ctx2 = logcmdutil.revsingle(repo, to_rev, None)
     else:
         ctx1a, ctx2 = logcmdutil.revpair(repo, revs)
         if not revs: