diff -r b7444cfc2c05 -r 8cce9f77ca73 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Wed Jul 29 10:42:09 2020 -0700
+++ b/mercurial/cmdutil.py	Thu Jul 16 13:33:46 2020 -0700
@@ -3375,7 +3375,7 @@
 
 def buildcommittemplate(repo, ctx, subs, extramsg, ref):
     ui = repo.ui
-    spec = formatter.templatespec(ref, None, None)
+    spec = formatter.reference_templatespec(ref)
     t = logcmdutil.changesettemplater(ui, repo, spec)
     t.t.cache.update(
         (k, templater.unquotestring(v))