We changed the Jenkins configuration to pull from GitLab while the mirroring to Gitolite was not working: jenkins-jobs@4db52b22
But we did not adjust this post-receive hook accordingly, so the "pushing to Git triggers a Jenkins build" behavior is broken.
Let's repair this, until we make up our mind (sysadmin#17715 (closed)) wrt. whether we should keep pointing Jenkins to GitLab's tails/tails, or use the local mirror we have on puppet-git.lizard.