Prevent 500 error when browse wiki page with repo access

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/shared/_clone_panel.html.haml

@@ -4,7 +4,8 @@
     %button{class: "btn #{ 'active' if default_clone_protocol == 'ssh' }", :"data-clone" => project.ssh_url_to_repo} SSH
     %button{class: "btn #{ 'active' if default_clone_protocol == 'http' }", :"data-clone" => project.http_url_to_repo}= gitlab_config.protocol.upcase
   = text_field_tag :project_clone, default_url_to_repo(project), class: "one_click_select form-control", readonly: true
-  .input-group-addon
-    .visibility-level-label.has_tooltip{'data-title' => "#{visibility_level_label(project.visibility_level)} project" }
-      = visibility_level_icon(project.visibility_level)
-      = visibility_level_label(project.visibility_level).downcase
+  - if project.kind_of?(Project)
+    .input-group-addon
+      .visibility-level-label.has_tooltip{'data-title' => "#{visibility_level_label(project.visibility_level)} project" }
+        = visibility_level_icon(project.visibility_level)
+        = visibility_level_label(project.visibility_level).downcase