Support 'uploadpack.allowReachableSHA1InWant' and/or 'uploadpackallowanysha1inwant'
Description
As part of our solution for building a large (mono) repository out of submodules (see our open-source project git-meta for more information), we need the ability to directly fetch commits by their SHAs. As this capability is supported by Git, we believe it to be a reasonable feature for you to provide. 'uploadpackallowanysha1inwant' is relatively new, but we would be satisfied with 'uploadpack.allowReachableSHA1InWant' for now; it's less efficient (reachability needs to be verified) but sufficient.
Proposal
If this feature is not on your roadmap we will submit a patch ourselves; we have not started looking at the code yet.
Links / references
Original support request: https://support.gitlab.com/hc/en-us/requests/55672
Our open-source project documenting our strategy: https://github.com/twosigma/git-meta
Relevant Git documentation: https://git-scm.com/docs/git-fetch-pack