--- a/mercurial/commands.py	Tue Oct 13 14:16:21 2020 -0400
+++ b/mercurial/commands.py	Sat Oct 17 21:57:21 2020 +0900
@@ -2351,7 +2351,7 @@
     ]
     + walkopts
     + dryrunopts,
-    _(b'[OPTION]... SOURCE... DEST'),
+    _(b'[OPTION]... (SOURCE... DEST | --forget DEST...)'),
     helpcategory=command.CATEGORY_FILE_CONTENTS,
 )
 def copy(ui, repo, *pats, **opts):