Re: [PATCH] Documentation: mark `--object-format=sha256` as experimental

Martin Ågren [off-list ref] writes:

quoted

I'm fine with marking the functionality experimental for a few releases,
since it is possible we have bugs people haven't found, and adding a
note about interoperability after that point, since I think that's a
fair and valuable issue.  I think if we go a few releases without any
major issues, we can change this to the following:

  Note that a SHA-256 repository cannot yet share work with "regular"
  SHA-1 repositories.  Many tools do not yet understand SHA-256
  repositories, so users may wish to take this into account when
  creating new repositories.

With respect, I think that's too aggressive. By that time, we may
conclude that, e.g., the "v2 pack indices with SHA-256" file handling is
robust. But I'd be surprised if using `git init --object-format=sha256`
in June 2021 won't cause *some* extra work for users or ourselves
further down the line compared to using a regular SHA-1 `git init`.
Pushing to a SHA-1 hosting service will become *possible* at some point,
but maybe it won't be *efficient enough to be practical in the real
world* until some time after that.

IOW, you question "if we go a few releases without any major issues"
part?  I tend to agree that for a large change like this, a few
releases may not be sufficiently long time for a feature that is
marked as experimental in big flashing red letters to get exercised
enough to get major issues noticed.

All those other, *new* file formats outlined in the hash
transition document won't exist at that time (at least not in master).

Now would probably be a good time to update the hash transition
documents, first of all to tick off what we've already done, and second,
to reassess the rest.

Yes, it is a good idea to stop and see where in the overall large
picture we currently are.

Thanks.