Get CI status when source and target project are different

After created a merge request from a forked repo, it shows `Cannot connect to CI server. Please check your setting` on the merge request page.

This issue is probably related to: 
* https://github.com/gitlabhq/gitlabhq/issues/4764#issuecomment-22614158
* https://groups.google.com/forum/#!topic/gitlabhq/EHxDsHCqKKo