dirstate: use `dirstate.change_files` to scope the change in `forget`

This is the way.

mercurial/commands.py

@@ -2966,7 +2966,7 b' def forget(ui, repo, *pats, **opts):'
     if not pats:
         raise error.InputError(_(b'no files specified'))
 
-    with repo.wlock():
+    with repo.wlock(), repo.dirstate.changing_files(repo):
         m = scmutil.match(repo[None], pats, opts)
         dryrun, interactive = opts.get(b'dry_run'), opts.get(b'interactive')
         uipathfn = scmutil.getuipathfn(repo, legacyrelativevalue=True)