Check if the key could really download, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7383#note_18518792

lib/gitlab/git_access.rb

@@ -45,7 +45,7 @@ module Gitlab
     def download_access_check
       if deploy_key
-        true
+        deploy_key.has_access_to?(project)
       elsif user
         user_download_access_check
       elsif Guest.can?(:download_code, project)