Can we make runner use git-clone(1) again

In the Gitaly team we've been working on implementing bundle URI support. This works, but only for git-clone(1), and not for git-fetch(1). In git#271 we've been trying to upstream changes so git-fetch(1) also uses bundles, but we are running in questionable design choices. It might take months before we find a viable solution.

Maybe it's quicker to make gitlab-runner use git-clone(1) again. At some point it used git-clone(1) but it was changed to git-init(1) + git-fetch(1) for some reason. Changing it back to git-clone(1) would allow us to benefit from bundle URIs.