Don't pass the actor for deploy key, feedback:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/7383#note_19579483

lib/gitlab/git_access.rb

@@ -189,6 +189,8 @@ module Gitlab
         case actor
         when User
           actor
+        when DeployKey
+          nil
         when Key
           actor.user
         end