discourse: Fix the public directory path reported by Discourse

Change the path to the public directory reported by Discourse
to its real path instead of the symlink in the store, since
the store path won't be matched by any nginx rules.

Fixes #142528.

(cherry picked from commit 1fb77e822b87b0ca729c007e63166c7d2d38e947)

pkgs/servers/web-apps/discourse/default.nix

@@ -265,6 +265,11 @@ let
 
       # Make sure the notification email setting applies
       ./notification_email.patch
+
+      # Change the path to the public directory reported by Discourse
+      # to its real path instead of the symlink in the store, since
+      # the store path won't be matched by any nginx rules
+      ./public_dir_path.patch
     ];
 
     postPatch = ''

pkgs/servers/web-apps/discourse/public_dir_path.patch

@@ -0,0 +1,13 @@
+diff --git a/lib/file_store/local_store.rb b/lib/file_store/local_store.rb
+index 25649532c0..614e062dc1 100644
+--- a/lib/file_store/local_store.rb
++++ b/lib/file_store/local_store.rb
+@@ -88,7 +88,7 @@ module FileStore
+     end
+ 
+     def public_dir
+-      File.join(Rails.root, "public")
++      "/run/discourse/public"
+     end
+ 
+     def tombstone_dir