These templates need to have a %s in them.

--- ghc-8.6.5/docs/users_guide/ghc_config.py.in	2019-04-07 20:39:58.000000000 +0100
+++ ghc-8.6.5/docs/users_guide/ghc_config.py.in	2025-07-07 12:15:36.541020822 +0100
@@ -1,6 +1,6 @@
 extlinks = {
-    'ghc-ticket': ('https://ghc.haskell.org/trac/ghc/ticket/%s', 'Trac #'),
-    'ghc-wiki': ('https://ghc.haskell.org/trac/ghc/wiki/%s', 'Trac #'),
+    'ghc-ticket': ('https://ghc.haskell.org/trac/ghc/ticket/%s', 'Trac #%s'),
+    'ghc-wiki': ('https://ghc.haskell.org/trac/ghc/wiki/%s', 'Trac #%s'),
 }
 
 libs_base_uri = '../libraries'