copy: correct synopsis by making SOURCE a required argument

mercurial/commands.py

@@ -1857,7 +1857,7 b' def config(ui, repo, *values, **opts):'
     [('A', 'after', None, _('record a copy that has already occurred')),
     ('f', 'force', None, _('forcibly copy over an existing managed file')),
     ] + walkopts + dryrunopts,
-    _('[OPTION]... [SOURCE]... DEST'),
+    _('[OPTION]... SOURCE... DEST'),
     helpcategory=command.CATEGORY_FILE_CONTENTS)
 def copy(ui, repo, *pats, **opts):
     """mark files as copied for the next commit