Can you allow git fetching specific commits?
The specific set of commands im looking at are
mkdir -p phabricator_git_repo && cd phabricator_git_repo && git init && git remote add origin https://we.phorge.it/source/phorge.git && git fetch origin b11c6fcacd8bceafc2a2f223037952dc817f4d7f && git reset --hard FETCH_HEAD && rm -rf .git && true
this commit does exist https://we.phorge.it/rPb11c6fcacd8bceafc2a2f223037952dc817f4d7f
we use a build system which fetches the code from a git repo and makes it available to the next stage of the build
From reading the git code, looks like there is a flag to allow this feature - uploadpack.allowReachableSHA1InWant, though I'll need to check that it actually works.
BTW, you'll save some time (and our bandwidth) if you add --depth 1 to the fetch phase.
(We'll also have a GitHub mirror at some point you could fetch from, they support this feature).