Re: [PATCH 1/1] bitbake: add BB_GIT_SHALLOW_SKIP_FAST to disable fast shallow mode

Hello,

We want to create a download mirror to store all sources needed to build a
specific project.

The idea is to use Git shallow tarballs because each tarball has a unique name.
This prevents files from being overwritten in the mirror. With full Git
tarballs, the name is always the same, so the mirror file gets replaced each
time. If something is removed from the upstream repository, we might upload a
new tarball that no longer contains a reference used by a recipe that was
already integrated.

With shallow tarballs, we can safely clean DL_DIR since it's not the source of
truth. If something is removed from upstream, we fall back to the mirror and
use the shallow tarball.

For most of the builds, we want to use the bare clone in DL_DIR/git2 and just
update the repo when bumping a SRCREV. The DL_DIR/git2 repositories are
available on the machine that triggers the build.

The shallow tarball is a fallback for cases where something was removed from
the repository (for example, after a force push) and is not present in
DL_DIR/git2 or upstream, but was merged at some point. This is why we use Git
shallow and set shallow_skip_fast to True.

Best regards,
Marcio