Bug: `git remote show <remote>` reports different HEAD branch than refs/remotes/<remote>/HEAD

Bug: `git remote show <remote>` reports different HEAD branch than refs/remotes/<remote>/HEAD

[Jason Karns]

I have a git repo that shows a different branch in
`.git/refs/remotes/origin/HEAD` than is reported by `git remote show
origin`.

The branch is `github-rename` in refs/remotes/origin/HEAD, but shows
`master` in output of git-remote-show

```
$ cat .git/refs/remotes/origin/HEAD
ref: refs/remotes/origin/github-rename

$ git remote show origin
* remote origin
  Fetch URL: git@XXXX.git
  Push  URL: git@XXXX.git
  HEAD branch: master
  Remote branches:
    github-rename     tracked
    master            tracked
    qa                tracked
    refactor-test     tracked
  Local branches configured for 'git pull':
    github-rename merges with remote github-rename
    master        merges with remote master
  Local refs configured for 'git push':
    github-rename pushes to github-rename (up to date)
    master        pushes to master        (up to date)
```

git version 2.14.1


Background:

Prior to my repo being cloned, the default branch was configured to be
`some-random-branch` on github. My repo was cloned and the HEAD branch
was set to `some-random-branch` correctly (in `refs/`). However,
git-remote-show reported `master` as the HEAD branch.

Later, `some-random-branch` was deleted from the remote. It _remained_
as the HEAD branch locally according to `refs/`.

In order to test the remote-show command, I changed the HEAD branch to
a branch that actually existed by running `git remote set-head origin
github-rename`. It changed the HEAD branch in `refs/` but remote-show
continues to report `master` as the remote's HEAD.


Thanks,
Jason Karns

Re: Bug: `git remote show <remote>` reports different HEAD branch than refs/remotes/<remote>/HEAD

[Igor Djordjevic]

Hi Jason,

On 15/08/2017 16:26, Jason Karns wrote:
> I have a git repo that shows a different branch in
> `.git/refs/remotes/origin/HEAD` than is reported by `git remote show
> origin`.
> 
> The branch is `github-rename` in refs/remotes/origin/HEAD, but shows
> `master` in output of git-remote-show
> 
> ```
> $ cat .git/refs/remotes/origin/HEAD
> ref: refs/remotes/origin/github-rename
> 
> $ git remote show origin
> * remote origin
>   Fetch URL: git@XXXX.git
>   Push  URL: git@XXXX.git
>   HEAD branch: master
>   Remote branches:
>     github-rename     tracked
>     master            tracked
>     qa                tracked
>     refactor-test     tracked
>   Local branches configured for 'git pull':
>     github-rename merges with remote github-rename
>     master        merges with remote master
>   Local refs configured for 'git push':
>     github-rename pushes to github-rename (up to date)
>     master        pushes to master        (up to date)
> ```
> 
> git version 2.14.1
> 
> 
> Background:
> 
> Prior to my repo being cloned, the default branch was configured to be
> `some-random-branch` on github. My repo was cloned and the HEAD branch
> was set to `some-random-branch` correctly (in `refs/`). However,
> git-remote-show reported `master` as the HEAD branch.
> 
> Later, `some-random-branch` was deleted from the remote. It _remained_
> as the HEAD branch locally according to `refs/`.
> 
> In order to test the remote-show command, I changed the HEAD branch to
> a branch that actually existed by running `git remote set-head origin
> github-rename`. It changed the HEAD branch in `refs/` but remote-show
> continues to report `master` as the remote's HEAD. 

I am no expert here, but reading the docs, it seems like you may have 
wrong expectations.

Documentation for "git remote set-head"[1] explains that this command 
is used to set default remote branch (locally), where later you can 
use remote name only to specify that specific (remote) branch instead.

Example shows that for remote named "origin", if you set default 
branch name to "master" (actually being "origin/master" locally), 
then whenever you want to type "origin/master", you can type "origin" 
only instead (set default branch name is implied).

For the given example, that is what you can see inside 
"refs/remotes/origin/HEAD", being set to "refs/remotes/origin/master".

So it is something _you_ set _locally_ to aid you in working with the 
remote repository.

On the other hand, what "git remote show" outputs for HEAD is a name 
of actually checked-out branch inside that remote repository - it`s 
what`s stored inside HEAD file of the remote repository root.

So it is something set on the _remote_ end, you can`t influence it 
from your local repository.

What you _could_ do in your specific case, as you mention using 
GitHub, is following their help page for "setting the default 
branch"[2] for your GitHub repository (which you track locally as 
"origin") to "github-rename".

(in general, non-GitHub repository case, one could usually run there 
either `git checkout github-rename`, if it`s not a bare repository, 
or `git symbolic-ref HEAD refs/heads/github-rename`, if it`s a bare 
repository)

Afterwards, running `git remote show origin` inside your local 
repository should output "github-rename" as HEAD value, as desired.

p.s. To set your default remote branch locally to checked-out branch 
on the remote end automatically, you can use `git remote set-head 
origin --auto`, as documented[1]. It will inspect what`s inside 
"HEAD" of the remote named "origin", and update your local 
"refs/remotes/origin/HEAD" accordingly.

[1] https://git-scm.com/docs/git-remote#git-remote-emset-headem
[2] https://help.github.com/articles/setting-the-default-branch/

Regards,
Buga

Re: Bug: `git remote show <remote>` reports different HEAD branch than refs/remotes/<remote>/HEAD

[Jason Karns]

On Tue, Aug 15, 2017 at 1:09 PM, Igor Djordjevic
<igor.d.djordjevic@gmail.com> wrote:
> Hi Jason,
>
> On 15/08/2017 16:26, Jason Karns wrote:
>> I have a git repo that shows a different branch in
>> `.git/refs/remotes/origin/HEAD` than is reported by `git remote show
>> origin`.
>>
>> The branch is `github-rename` in refs/remotes/origin/HEAD, but shows
>> `master` in output of git-remote-show
>>
>> ```
>> $ cat .git/refs/remotes/origin/HEAD
>> ref: refs/remotes/origin/github-rename
>>
>> $ git remote show origin
>> * remote origin
>>   Fetch URL: git@XXXX.git
>>   Push  URL: git@XXXX.git
>>   HEAD branch: master
>>   Remote branches:
>>     github-rename     tracked
>>     master            tracked
>>     qa                tracked
>>     refactor-test     tracked
>>   Local branches configured for 'git pull':
>>     github-rename merges with remote github-rename
>>     master        merges with remote master
>>   Local refs configured for 'git push':
>>     github-rename pushes to github-rename (up to date)
>>     master        pushes to master        (up to date)
>> ```
>>
>> git version 2.14.1
>>
>>
>> Background:
>>
>> Prior to my repo being cloned, the default branch was configured to be
>> `some-random-branch` on github. My repo was cloned and the HEAD branch
>> was set to `some-random-branch` correctly (in `refs/`). However,
>> git-remote-show reported `master` as the HEAD branch.
>>
>> Later, `some-random-branch` was deleted from the remote. It _remained_
>> as the HEAD branch locally according to `refs/`.
>>
>> In order to test the remote-show command, I changed the HEAD branch to
>> a branch that actually existed by running `git remote set-head origin
>> github-rename`. It changed the HEAD branch in `refs/` but remote-show
>> continues to report `master` as the remote's HEAD.
>
> I am no expert here, but reading the docs, it seems like you may have
> wrong expectations.
>
> Documentation for "git remote set-head"[1] explains that this command
> is used to set default remote branch (locally), where later you can
> use remote name only to specify that specific (remote) branch instead.
>
> Example shows that for remote named "origin", if you set default
> branch name to "master" (actually being "origin/master" locally),
> then whenever you want to type "origin/master", you can type "origin"
> only instead (set default branch name is implied).
>
> For the given example, that is what you can see inside
> "refs/remotes/origin/HEAD", being set to "refs/remotes/origin/master".
>
> So it is something _you_ set _locally_ to aid you in working with the
> remote repository.


Cool, this is all to my expectations.

>
> On the other hand, what "git remote show" outputs for HEAD is a name
> of actually checked-out branch inside that remote repository - it`s
> what`s stored inside HEAD file of the remote repository root.
>
> So it is something set on the _remote_ end, you can`t influence it
> from your local repository.


So _this_ is not what I expected. Thanks for clarifying.

Considering that a fresh clone replicates the remote's default branch
as the local default for that remote, I wager (in the majority of
cases) that these two are the same. It would seem that what I would
like in this case is a feature change to git-remote-show to show both
the locally-configured and remote-configured defaults for the given
remote (similar in spirit to how git-remote-show already shows local
vs remote information: branches and their configurations for
push/pull).

Such a feature would be the "read" side of the remote set-head
command, and also be useful for highlighting cases where the local and
remote defaults do not match.

If I might suggest adding "Local default branch: xxx" to the
remote-show output, following the HEAD branch output. (Perhaps,
printing "(not set)" if the default isn't configured locally.)

````
$ git remote show origin | head
* remote origin
  Fetch URL: git@XXXX
  Push  URL: git@XXXX
  HEAD branch: develop
  Local default branch: foo
  Remote branches:
```

Or perhaps adding a line at the bottom with the other local refs. That
would allow additional notices when/if the local and remote defaults
differ.

>
> What you _could_ do in your specific case, as you mention using
> GitHub, is following their help page for "setting the default
> branch"[2] for your GitHub repository (which you track locally as
> "origin") to "github-rename".
>
> (in general, non-GitHub repository case, one could usually run there
> either `git checkout github-rename`, if it`s not a bare repository,
> or `git symbolic-ref HEAD refs/heads/github-rename`, if it`s a bare
> repository)
>
> Afterwards, running `git remote show origin` inside your local
> repository should output "github-rename" as HEAD value, as desired.
>

In my case, the github configuration is correct, and the set-head
command was only used to test the output of git-remote-show. The crux
of my misunderstanding is that I thought git-remote-show should be
reporting the contents of `refs/remotes/origin/HEAD`. Having that
information reported somehow (preferably through git-remote-show)
would have clarified this for me.


> p.s. To set your default remote branch locally to checked-out branch
> on the remote end automatically, you can use `git remote set-head
> origin --auto`, as documented[1]. It will inspect what`s inside
> "HEAD" of the remote named "origin", and update your local
> "refs/remotes/origin/HEAD" accordingly.
>
> [1] https://git-scm.com/docs/git-remote#git-remote-emset-headem
> [2] https://help.github.com/articles/setting-the-default-branch/
>
> Regards,
> Buga

Thanks for clarifying. Having this information surfaced a bit would be
a nice improvement, IMO.

Jason

Re: Bug: `git remote show <remote>` reports different HEAD branch than refs/remotes/<remote>/HEAD

[Jeff King]

On Tue, Aug 15, 2017 at 01:58:38PM -0400, Jason Karns wrote:

> > On the other hand, what "git remote show" outputs for HEAD is a name
> > of actually checked-out branch inside that remote repository - it`s
> > what`s stored inside HEAD file of the remote repository root.
> >
> > So it is something set on the _remote_ end, you can`t influence it
> > from your local repository.
> 
> So _this_ is not what I expected. Thanks for clarifying.
> 
> Considering that a fresh clone replicates the remote's default branch
> as the local default for that remote, I wager (in the majority of
> cases) that these two are the same. It would seem that what I would
> like in this case is a feature change to git-remote-show to show both
> the locally-configured and remote-configured defaults for the given
> remote (similar in spirit to how git-remote-show already shows local
> vs remote information: branches and their configurations for
> push/pull).

Yes, I'd agree. This seems like exactly the kind of information that
"remote show" was intended to display.

It should be a pretty straight-forward patch for anybody wanting to get
their feet wet in git development. The trickier half of showing both is
getting the remote information, but we're already doing that. So I think
any patch would want to:

  1. Teach builtin/remote.c:show() to say "Remote HEAD branch" instead
     of just "HEAD branch".

  2. Add a "Local HEAD branch" that shows the local symref. That symref
     is always refs/remotes/<remotename>/HEAD, which can be constructed
     with a strbuf. And then resolve_refdup() can be used to get the
     pointed-to ref (check the returned flags for REF_ISSYMREF, and
     the string return value is the refname).

-Peff