fix UsersControllerTest failure randomly

fix UsersControllerTest failure randomly

<pre>
  1) Error:
UsersControllerTest#test_show:
ActionView::Template::Error: undefined method `name' for nil:NilClass
    app/models/issue.rb:53:in `block in <class:Issue>'
    lib/plugins/acts_as_event/lib/acts_as_event.rb:62:in `call'
    lib/plugins/acts_as_event/lib/acts_as_event.rb:62:in `event_title'
    app/views/users/show.html.erb:57:in `block (2 levels) in _app_views_users_show_html_erb___2965700471773239267_46119700'
    app/views/users/show.html.erb:53:in `each'
    app/views/users/show.html.erb:53:in `block in _app_views_users_show_html_erb___2965700471773239267_46119700'
    app/views/users/show.html.erb:50:in `each'
    app/views/users/show.html.erb:50:in `_app_views_users_show_html_erb___2965700471773239267_46119700'
    app/controllers/users_controller.rb:75:in `block (2 levels) in show'
    app/controllers/users_controller.rb:71:in `show'
    test/functional/users_controller_test.rb:76:in `test_show'
</pre>

This can be reproduced with following change.

<pre>
   fixtures :users, :projects, :members, :member_roles, :roles,
            :custom_fields, :custom_values, :groups_users,
-           :auth_sources
+           :auth_sources,
+           :enabled_modules,
+           :issues, :issue_statuses
</pre>

git-svn-id: http://svn.redmine.org/redmine/trunk@13883 e93f8b46-1217-0410-a6f0-8f06a7374b81