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

>> 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.

> 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.