patchrename default branch from 'master' to 'main' in refs and test scripts

> diff --git a/remote.c b/remote.c
> index 81d8fc017e1..ffc4089a1c2 100644
> --- a/remote.c
> +++ b/remote.c
> @@ -2379,7 +2379,7 @@ struct ref *guess_remote_head(const struct ref *head,
>  			return copy_ref(r);
>  
>  		/* Fall back to the hard-coded historical default */
> -		r = find_ref_by_name(refs, "refs/heads/master");
> +		r = find_ref_by_name(refs, "refs/heads/main");

> From: Wing Huang <huangsen365@gmail.com>
> 
> Signed-off-by: Wing Huang <huangsen365@gmail.com>
> 
> 	modified:   refs.c
> 	modified:   remote.c
> 	modified:   t/test-lib.sh
> ---
>      rename default branch from 'master' to 'main' in refs and test scripts
>      
>      This patch updates Git's default branch name from 'master' to 'main' to
>      align with modern naming conventions adopted across the industry.

>      Compatibility notes:
>      
>       * Existing repositories are unaffected
>       * Users can still set init.defaultBranch=master if preferred
>       * The change only applies to new git init operations when no explicit
>         branch name is configured
>      
>      This follows the precedent set when init.defaultBranch configuration was
>      introduced in Git 2.28, which already acknowledged the community's move
>      toward more inclusive default branch names.
> 
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1961%2Fhuangsen365%2Fmaster-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1961/huangsen365/master-v1
> Pull-Request: https://github.com/gitgitgadget/git/pull/1961
> 
>   refs.c        | 2 +-
>   remote.c      | 2 +-
>   t/test-lib.sh | 2 +-
>   3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/refs.c b/refs.c
> index 4ff55cf24f6..929e9ce60c6 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -653,7 +653,7 @@ char *repo_default_branch_name(struct repository *r, int quiet)
>   		die(_("could not retrieve `%s`"), config_display_key);
>   
>   	if (!ret) {
> -		ret = xstrdup("master");
> +		ret = xstrdup("main");
>   		if (!quiet)
>   			advise_if_enabled(ADVICE_DEFAULT_BRANCH_NAME,
>   					  _(default_branch_name_advice), ret);
> diff --git a/remote.c b/remote.c
> index 81d8fc017e1..ffc4089a1c2 100644
> --- a/remote.c
> +++ b/remote.c
> @@ -2379,7 +2379,7 @@ struct ref *guess_remote_head(const struct ref *head,
>   			return copy_ref(r);
>   
>   		/* Fall back to the hard-coded historical default */
> -		r = find_ref_by_name(refs, "refs/heads/master");
> +		r = find_ref_by_name(refs, "refs/heads/main");
>   		if (r && oideq(&r->old_oid, &head->old_oid))
>   			return copy_ref(r);
>   	}
> diff --git a/t/test-lib.sh b/t/test-lib.sh
> index 621cd31ae1d..4e273a6e94d 100644
> --- a/t/test-lib.sh
> +++ b/t/test-lib.sh
> @@ -129,7 +129,7 @@ fi
>   
>   # Explicitly set the default branch name for testing, to avoid the
>   # transitory "git init" warning under --verbose.
> -: ${GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME:=master}
> +: ${GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME:=main}
>   export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
>   
>   ################################################################
> 
> base-commit: 1fa68948c3d76328236cac73d2adf33c905bd8e3

> >       * remote.c: Update fallback branch name for remote operations
> 
> I think we want to keep the fallback to "master" but check for "main" first.
> Otherwise we'll stop finding the default branch where the remote is still
> using master.

> > @@ -2379,7 +2379,7 @@ struct ref *guess_remote_head(const struct ref *head,
> >   			return copy_ref(r);
> >   		/* Fall back to the hard-coded historical default */
> > -		r = find_ref_by_name(refs, "refs/heads/master");
> > +		r = find_ref_by_name(refs, "refs/heads/main");
> >   		if (r && oideq(&r->old_oid, &head->old_oid))
> >   			return copy_ref(r);

> On Tue, Aug 26, 2025 at 10:58:55AM +0100, Phillip Wood wrote:
> 
>>>        * remote.c: Update fallback branch name for remote operations
>>
>> I think we want to keep the fallback to "master" but check for "main" first.
>> Otherwise we'll stop finding the default branch where the remote is still
>> using master.
> 
> I'm not sure we need to change anything there. Modern Git will generally
> report the name of the branch pointed to by HEAD back to the client
> (using either a symref capability in protocol v0 or the symref extension
> to the ls-refs list in v2). So the fallback would be needed only for
> very old servers, in which case "master" is probably a better guess.
> 
> IIRC, there are cases where v0 does not report the HEAD value when it
> points to an unborn branch (and while I'd expect most Git servers to
> always support v2 these days, sometimes the protocol upgrade fails due
> to things like ssh blocking the GIT_PROTOCOL variable). But I don't
> think that would affect the fallback code:

>>> @@ -2379,7 +2379,7 @@ struct ref *guess_remote_head(const struct ref *head,
>>>    			return copy_ref(r);
>>>    		/* Fall back to the hard-coded historical default */
>>> -		r = find_ref_by_name(refs, "refs/heads/master");
>>> +		r = find_ref_by_name(refs, "refs/heads/main");
>>>    		if (r && oideq(&r->old_oid, &head->old_oid))
>>>    			return copy_ref(r);
> 
> since it is only about looking for the matching branch name, and not the
> unborn case.
> 
> If we truly have an unborn HEAD on a very old server (with no protocol
> support), I think we just end up without checking anything out, which
> means HEAD would default to whatever the local client default is.

> On 26/08/2025 05:52, Wing Huang via GitGitGadget wrote:
>> From: Wing Huang <huangsen365@gmail.com>
>>
>>      rename default branch from 'master' to 'main' in refs and test 
>> scripts
>>      This patch updates Git's default branch name from 'master' to 
>> 'main' to
>>      align with modern naming conventions adopted across the industry.
> 
> Thank you for your interest in this. We're currently planning to change 
> the default branch name when Git 3.0 is released as documented in 
> Documentation/BreakingChanges.adoc.