Fix various bugs related to relative_url_root in development

app/views/peek/_bar.html.haml

@@ -2,6 +2,6 @@
 
 #js-peek{ data: { env: Peek.env,
          request_id: Peek.request_id,
-         peek_url: peek_routes.results_url,
+         peek_url: "#{peek_routes_path}/results",
          profile_url: url_for(safe_params.merge(lineprofiler: 'true')) },
          class: Peek.env }

lib/gitlab/gon_helper.rb

@@ -11,7 +11,7 @@ module Gitlab
       gon.asset_host             = ActionController::Base.asset_host
       gon.webpack_public_path    = webpack_public_path
       gon.relative_url_root      = Gitlab.config.gitlab.relative_url_root
-      gon.shortcuts_path         = help_page_path('shortcuts')
+      gon.shortcuts_path         = Gitlab::Routing.url_helpers.help_page_path('shortcuts')
       gon.user_color_scheme      = Gitlab::ColorSchemes.for_user(current_user).css_class
       gon.sentry_dsn             = Gitlab::CurrentSettings.clientside_sentry_dsn if Gitlab::CurrentSettings.clientside_sentry_enabled
       gon.gitlab_url             = Gitlab.config.gitlab.url

lib/gitlab/webpack/dev_server_middleware.rb

@@ -15,6 +15,11 @@ module Gitlab
 
       def perform_request(env)
         if @proxy_path && env['PATH_INFO'].start_with?("/#{@proxy_path}")
+          if relative_url_root = Rails.application.config.relative_url_root
+            env['SCRIPT_NAME'] = ""
+            env['REQUEST_PATH'].sub!(/\A#{Regexp.escape(relative_url_root)}/, '')
+          end
+
           super(env)
         else
           @app.call(env)