Fix application crashes after #2772

app/controllers/admin/users_controller.rb

 class Admin::UsersController < Admin::ApplicationController
+  before_filter :admin_user, only: [:show, :edit, :update, :destroy]
+
   def index
     @admin_users = User.scoped
     @admin_users = @admin_users.filter(params[:filter])
@@ -7,11 +9,8 @@ class Admin::UsersController < Admin::ApplicationController
   end
 
   def show
-    projects = if admin_user.authorized_projects.empty?
-               Project
-             else
-               Project.without_user(admin_user)
-             end.all
+    @projects = Project.scoped
+    @projects = @projects.without_user(admin_user) if admin_user.authorized_projects.empty?
   end
 
   def team_update
@@ -102,6 +101,6 @@ class Admin::UsersController < Admin::ApplicationController
   protected
 
   def admin_user
-    @admin_user ||= User.find_by_username(params[:id])
+    @admin_user ||= User.find_by_username!(params[:id])
   end
 end

config/routes.rb

@@ -49,7 +49,7 @@ Gitlab::Application.routes.draw do
   # Admin Area
   #
   namespace :admin do
-    resources :users do
+    resources :users, constraints: { id: /[a-zA-Z.\/0-9_\-]+/ } do
       member do
         put :team_update
         put :block