Merge branch '60965-referencing-issues-or-epics-by-url-fails-with-404' into 'master'

Resolve "Referencing issues or epics by URL fails with 404"

Closes #61099 and #60965

See merge request gitlab-org/gitlab-ce!27827

config/initializers/1_settings.rb

@@ -136,6 +136,8 @@ Settings.gitlab['ssh_host']   ||= Settings.gitlab.host
 Settings.gitlab['https']        = false if Settings.gitlab['https'].nil?
 Settings.gitlab['port']       ||= ENV['GITLAB_PORT'] || (Settings.gitlab.https ? 443 : 80)
 Settings.gitlab['relative_url_root'] ||= ENV['RAILS_RELATIVE_URL_ROOT'] || ''
+# / is not a valid relative URL root
+Settings.gitlab['relative_url_root']   = '' if Settings.gitlab['relative_url_root'] == '/'
 Settings.gitlab['protocol'] ||= Settings.gitlab.https ? "https" : "http"
 Settings.gitlab['email_enabled'] ||= true if Settings.gitlab['email_enabled'].nil?
 Settings.gitlab['email_from'] ||= ENV['GITLAB_EMAIL_FROM'] || "gitlab@#{Settings.gitlab.host}"