diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4866,8 +4866,7 @@
 
     if node:
         node = scmutil.revsingle(repo, node).node()
-
-    if not node:
+    else:
         if ui.configbool(b'commands', b'merge.require-rev'):
             raise error.Abort(
                 _(