bug#66364: 29.1.50; vc-hg-registered/state are slow on directories of large repos

[Spencer Baugh]

>From 5573b678f816f81623deb7ebde66dfd3ebe92355 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh@janestreet.com>
Date: Thu, 5 Oct 2023 11:35:25 -0400
Subject: [PATCH] Optimize vc-hg-state for directories

Directories are never tracked in hg, so it's pointless to run
vc-hg-state on them.  And, in fact, our implementation previously
would list all the files contained in the directory and then parse
that in Emacs, which is very slow in large repos.

Let's just use the knowledge that directories aren't tracked in hg,
and skip running hg entirely.

* lisp/vc/vc-hg.el (vc-hg-state): Return unregistered for directories.
---
 lisp/vc/vc-hg.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/vc/vc-hg.el b/lisp/vc/vc-hg.el
index c3e563a1f10..9a30706f519 100644
--- a/lisp/vc/vc-hg.el
+++ b/lisp/vc/vc-hg.el
@@ -216,8 +216,10 @@ vc-hg-registered
 
 (defun vc-hg-state (file)
   "Hg-specific version of `vc-state'."
-  (let ((state (vc-hg-state-fast file)))
-    (if (eq state 'unsupported) (vc-hg-state-slow file) state)))
+  (if (file-directory-p file)
+      'unregistered
+    (let ((state (vc-hg-state-fast file)))
+      (if (eq state 'unsupported) (vc-hg-state-slow file) state))))
 
 (defun vc-hg-state-slow (file)
   "Determine status of FILE by running hg."
-- 
2.39.3