diff -r 402a6b6173e9 -r a51c522c0064 mercurial/commands.py
--- a/mercurial/commands.py	Tue Jan 18 14:57:15 2022 -0800
+++ b/mercurial/commands.py	Tue Jan 18 15:04:55 2022 -0800
@@ -4914,7 +4914,7 @@
     overrides = {(b'ui', b'forcemerge'): opts.get(b'tool', b'')}
     with ui.configoverride(overrides, b'merge'):
         force = opts.get(b'force')
-        labels = [b'working copy', b'merge rev']
+        labels = [b'working copy', b'merge rev', b'common ancestor']
         return hg.merge(ctx, force=force, labels=labels)