Build emails for push-based mirrored repos sent to owner of repo instead of pusher
Description
When you create a repo to use as CI/CD for an external repo (such as GitHub), the resulting build emails for pushes that come through the external repo always get sent to the user that originally created the mirror repo, instead of the user responsible for the push.
Proposal
Ideally, GitLab would integrate with the GitHub API to determine the email of the user responsible for pushing the repo and send the build email back to that user instead.
Alternatively, gitlab-ce#20718 might be good enough in practice. However, at the moment with neither of these implemented, it is impossible to set up a mirrored repo on GitLab and get the build notification emails sent to the right person.