Redirect favicon.(png|ico) to actual favicon asset or upload

config/routes.rb

@@ -11,6 +11,12 @@ Rails.application.routes.draw do
     post :toggle_award_emoji, on: :member
   end
+  favicon_redirect = redirect do |_params, _request|
+    ActionController::Base.helpers.asset_url(Gitlab::Favicon.main)
+  end
+  get 'favicon.png', to: favicon_redirect
+  get 'favicon.ico', to: favicon_redirect
+
   draw :sherlock
   draw :development
   draw :ci

doc/user/reserved_names.md

@@ -58,6 +58,7 @@ Currently the following names are reserved as top level groups:
 - dashboard
 - deploy.html
 - explore
+- favicon.ico
 - favicon.png
 - groups
 - header_logo_dark.png

lib/gitlab/path_regex.rb

@@ -30,6 +30,7 @@ module Gitlab
       dashboard
       deploy.html
       explore
+      favicon.ico
       favicon.png
       files
       groups