If we're bundling sources we really need to fetch from them because
we want to bundle shallow clones. However, this doesn't work for older
git versions, so pre-emptively fetch those deeply.
Closes: #62
Approved by: alexlarsson
There is no need to bundle the entire history in a git repo.
Instead we only bundle shallow versions of all the branches/tags/commit
that we reference.
For directly specified commit ids we can't really shallow-clone those,
so we create fake tags in the mirrored repo.
Mathieu Bridon