https://bugs.gentoo.org/889460
https://github.com/beetbox/beets/commit/2106f471affd1dab35b4b26187b9c74d034528c5

From 2106f471affd1dab35b4b26187b9c74d034528c5 Mon Sep 17 00:00:00 2001
From: Jack Wilsdon <jack.wilsdon@gmail.com>
Date: Sat, 31 Dec 2022 14:23:34 +0000
Subject: [PATCH] Add missing placeholders to extlinks captions

Sphinx 6.0.0 changed extlinks to always require placeholders in link
captions. See https://github.com/sphinx-doc/sphinx/commit/93cf1a57d916a1ff96c8e8a0356d0256e40489ac
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,10 +18,10 @@
 
 # External links to the bug tracker and other sites.
 extlinks = {
-    'bug': ('https://github.com/beetbox/beets/issues/%s', '#'),
-    'user': ('https://github.com/%s', ''),
-    'pypi': ('https://pypi.org/project/%s/', ''),
-    'stdlib': ('https://docs.python.org/3/library/%s.html', ''),
+    'bug': ('https://github.com/beetbox/beets/issues/%s', '#%s'),
+    'user': ('https://github.com/%s', '%s'),
+    'pypi': ('https://pypi.org/project/%s/', '%s'),
+    'stdlib': ('https://docs.python.org/3/library/%s.html', '%s'),
 }
 
 linkcheck_ignore = [