sshd support for Git protocol v2 (was: Re: Name for initial branch is ignored when repository is cloned with SSH)

> On Fri, Mar 15, 2024 at 10:49:39AM +0900, Yasuhiro Kimura wrote:
> 
>> I expect the change is committed to 'main' branch. But actually it is
>> committed to 'master' branch.
>>
>> Anything else you want to add:
>>
>> If I change step 2 as following,
>>
>> 2'. git clone /somewhere/test.git
>>
>> then I get expected behavior.
> 
> I suspect you are running afoul of two things:
> 
>    1. When cloning a totally empty repository, detecting the destination
>       of the unborn HEAD requires a protocol extension. This extension
>       was implemented only for Git's v2 protocol, not for v0.
> 
>    2. Git should automatically use v2 in most cases these days. But it
>       does so by probing the server in a backwards-compatible way to see
>       if it also supports v2. For ssh, that probe happens by passing a
>       special environment variable. However, the default config for many
>       ssh servers refuses unknown variables. For OpenSSH, you'd want to
>       add:
> 
>         AcceptEnv GIT_PROTOCOL
> 
>       to your sshd_config.