Git rebase no longer defaults to upstream after force push

Git rebase no longer defaults to upstream after force push

[Erik Cervin Edin]

Thank you for filling out a Git bug report!
Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)

  git init --bare foo.git && git clone foo.git/ foo && cd foo
  touch bar && git add bar && git commit -m init
  git push -u
  git switch -c a
  seq 1 3 > bar && git add bar && git commit -m 1
  git push
  seq 11 13 > bar && git add bar && git commit -m 2
  git rebase -ir # Works like git rebase -ir @{upstream}
  git push --force origin main:a
  git rebase -ir # No longer works like git rebase -ir @{upstream}

What did you expect to happen? (Expected behavior)

After force pushing, I still expected the rebase to work like git
rebase -ir @{upstream}.

What happened instead? (Actual behavior)

The rebase defaults to a commit other than that of the tip of the
upstream branch.

What's different between what you expected and what actually happened?

Instead of behaving like git rebase @{upstream}, the rebase seems to
default to rebasing on-top of the old upstream.

git rebase -ir result in a todo like this:

l onto

t onto
p f1cfbff 2023-04-18    2

Compared to git rebase -ir @{upstream} which results in a todo like this:

l onto

t onto
p 01e3c92 2023-04-18    1
p f1cfbff 2023-04-18    2

Anything else you want to add:

Please review the rest of the bug report below.
You can delete any lines you don't wish to share.


[System Info]
git version:
git version 2.40.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 5.15.90.1-microsoft-standard-WSL2 #1 SMP Fri Jan 27
02:56:13 UTC 2023 x86_64
compiler info: gnuc: 11.3
libc info: glibc: 2.35
$SHELL (typically, interactive shell): /bin/bash


[Enabled Hooks]

-- 
Erik Cervin-Edin

Re: Git rebase no longer defaults to upstream after force push

[Phillip Wood]

Hi Erik

Thanks for reporting this, unfortunately without knowing more about your 
config settings it is hard to tell what is happening here.

On 18/04/2023 10:17, Erik Cervin Edin wrote:
> Thank you for filling out a Git bug report!
> Please answer the following questions to help us understand your issue.
 >
> What did you do before the bug happened? (Steps to reproduce your issue)
> 
>    git init --bare foo.git && git clone foo.git/ foo && cd foo
>    touch bar && git add bar && git commit -m init
>    git push -u

This sets the upstream branch for main to origin/main, (assuming 
push.default allows pushing without specifying a refspec)

>    git switch -c a

Here you create a new branch, whether switch sets an upstream for it 
depends on the value of branch.autoSetupMerge. The default is not to set 
an upstream branch in this case. If you have set branch.autoSetupMerge 
to "always" then the upstream branch will be "main", if 
branch.autoSetupMerge is set to "inherit" then the upstream branch will 
be "origin/main". What does branch -vv show?

>    seq 1 3 > bar && git add bar && git commit -m 1
>    git push

What happens here depends on push.default, branch.autoSetupMerge and 
push.autoSetupRemote. If switch did not set an upstream branch then push 
will if you have push.autoSetupRemote enabled.

>    seq 11 13 > bar && git add bar && git commit -m 2
>    git rebase -ir # Works like git rebase -ir @{upstream}
>    git push --force origin main:a
>    git rebase -ir # No longer works like git rebase -ir @{upstream}

Without knowing what the upstream branch is it is hard to say what is 
going on here.

Best Wishes

Phillip

> What did you expect to happen? (Expected behavior)
> 
> After force pushing, I still expected the rebase to work like git
> rebase -ir @{upstream}.
> 
> What happened instead? (Actual behavior)
> 
> The rebase defaults to a commit other than that of the tip of the
> upstream branch.
> 
> What's different between what you expected and what actually happened?
> 
> Instead of behaving like git rebase @{upstream}, the rebase seems to
> default to rebasing on-top of the old upstream.
> 
> git rebase -ir result in a todo like this:
> 
> l onto
> 
> t onto
> p f1cfbff 2023-04-18    2
> 
> Compared to git rebase -ir @{upstream} which results in a todo like this:
> 
> l onto
> 
> t onto
> p 01e3c92 2023-04-18    1
> p f1cfbff 2023-04-18    2
> 
> Anything else you want to add:
> 
> Please review the rest of the bug report below.
> You can delete any lines you don't wish to share.
> 
> 
> [System Info]
> git version:
> git version 2.40.0
> cpu: x86_64
> no commit associated with this build
> sizeof-long: 8
> sizeof-size_t: 8
> shell-path: /bin/sh
> uname: Linux 5.15.90.1-microsoft-standard-WSL2 #1 SMP Fri Jan 27
> 02:56:13 UTC 2023 x86_64
> compiler info: gnuc: 11.3
> libc info: glibc: 2.35
> $SHELL (typically, interactive shell): /bin/bash
> 
> 
> [Enabled Hooks]
> 

Re: Git rebase no longer defaults to upstream after force push

[Cem Gündoğdu]

Hi Erik,

From documentation:

> If <upstream> is not specified, [...] and the --fork-point option is assumed.

The --fork-point option does this:

> Use reflog to find a better common ancestor between <upstream> and <branch> when calculating which commits have been introduced by <branch>.

Since the parent of a is still in the reflog of origin/a, it is not
being rebased (the rationale being that the commit *was* in origin/a
at some point). If you want to disable this behavior, add
--no-fork-point option:

git rebase -ir --no-fork-point

Since this is the documented behavior, it probably is not a bug.

Best,
Cem

On Tue, Apr 18, 2023 at 11:34 AM Erik Cervin Edin <erik@cervined.in> wrote:
>
> Thank you for filling out a Git bug report!
> Please answer the following questions to help us understand your issue.
>
> What did you do before the bug happened? (Steps to reproduce your issue)
>
>   git init --bare foo.git && git clone foo.git/ foo && cd foo
>   touch bar && git add bar && git commit -m init
>   git push -u
>   git switch -c a
>   seq 1 3 > bar && git add bar && git commit -m 1
>   git push
>   seq 11 13 > bar && git add bar && git commit -m 2
>   git rebase -ir # Works like git rebase -ir @{upstream}
>   git push --force origin main:a
>   git rebase -ir # No longer works like git rebase -ir @{upstream}
>
> What did you expect to happen? (Expected behavior)
>
> After force pushing, I still expected the rebase to work like git
> rebase -ir @{upstream}.
>
> What happened instead? (Actual behavior)
>
> The rebase defaults to a commit other than that of the tip of the
> upstream branch.
>
> What's different between what you expected and what actually happened?
>
> Instead of behaving like git rebase @{upstream}, the rebase seems to
> default to rebasing on-top of the old upstream.
>
> git rebase -ir result in a todo like this:
>
> l onto
>
> t onto
> p f1cfbff 2023-04-18    2
>
> Compared to git rebase -ir @{upstream} which results in a todo like this:
>
> l onto
>
> t onto
> p 01e3c92 2023-04-18    1
> p f1cfbff 2023-04-18    2
>
> Anything else you want to add:
>
> Please review the rest of the bug report below.
> You can delete any lines you don't wish to share.
>
>
> [System Info]
> git version:
> git version 2.40.0
> cpu: x86_64
> no commit associated with this build
> sizeof-long: 8
> sizeof-size_t: 8
> shell-path: /bin/sh
> uname: Linux 5.15.90.1-microsoft-standard-WSL2 #1 SMP Fri Jan 27
> 02:56:13 UTC 2023 x86_64
> compiler info: gnuc: 11.3
> libc info: glibc: 2.35
> $SHELL (typically, interactive shell): /bin/bash
>
>
> [Enabled Hooks]
>
> --
> Erik Cervin-Edin

Re: Git rebase no longer defaults to upstream after force push

[Erik Cervin Edin]

On Tue, Apr 18, 2023 at 5:54 PM Cem Gündoğdu <cscallsign@gmail.com> wrote:
> > If <upstream> is not specified, [...] and the --fork-point option is assumed.
>
> The --fork-point option does this:
>
> > Use reflog to find a better common ancestor between <upstream> and <branch> when calculating which commits have been introduced by <branch>.
>
> Since the parent of a is still in the reflog of origin/a, it is not
> being rebased (the rationale being that the commit *was* in origin/a
> at some point). If you want to disable this behavior, add
> --no-fork-point option:

Yes. That's it, thank you for pointing out --fork-point. That's indeed
what's causing the unexpected behavior.

Do you happen to know when such behavior is desirable? I'm tempted to
change the default to --no-fork-point but usually when something is
default there's a valid reason.. 🤔

Re: Git rebase no longer defaults to upstream after force push

[Sergey Organov]

Erik Cervin Edin <erik@cervined.in> writes:

> On Tue, Apr 18, 2023 at 5:54 PM Cem Gündoğdu <cscallsign@gmail.com> wrote:
>> > If <upstream> is not specified, [...] and the --fork-point option is assumed.
>>
>> The --fork-point option does this:
>>
>> > Use reflog to find a better common ancestor between <upstream> and
>> > <branch> when calculating which commits have been introduced by
>> > <branch>.
>>
>> Since the parent of a is still in the reflog of origin/a, it is not
>> being rebased (the rationale being that the commit *was* in origin/a
>> at some point). If you want to disable this behavior, add
>> --no-fork-point option:
>
> Yes. That's it, thank you for pointing out --fork-point. That's indeed
> what's causing the unexpected behavior.
>
> Do you happen to know when such behavior is desirable? I'm tempted to
> change the default to --no-fork-point but usually when something is
> default there's a valid reason.. 🤔

$ git help merge-base

has a thorough discussion of --fork-point that might be helpful.

As far as I understand, it helps to DWYM when remote branch has been
rewound, and causes nasty confusion when it fires unintentionally. 

-- Sergey

Re: Git rebase no longer defaults to upstream after force push

[Felipe Contreras]

Erik Cervin Edin wrote:
> Thank you for filling out a Git bug report!
> Please answer the following questions to help us understand your issue.
> 
> What did you do before the bug happened? (Steps to reproduce your issue)
> 
>   git init --bare foo.git && git clone foo.git/ foo && cd foo
>   touch bar && git add bar && git commit -m init
>   git push -u
>   git switch -c a
>   seq 1 3 > bar && git add bar && git commit -m 1
>   git push

For me it fails at this point.

  fatal: The upstream branch of your current branch does not match
  the name of your current branch.  To push to the upstream branch
  on the remote, use

      git push . HEAD:master

  To push to the branch of the same name on the remote, use

      git push . HEAD

  To choose either option permanently, see push.default in 'git help config'.

  To avoid automatically configuring an upstream branch when its name
  won't match the local branch, see option 'simple' of branch.autoSetupMerge
  in 'git help config'.

What's your configured push.default?

>   seq 11 13 > bar && git add bar && git commit -m 2
>   git rebase -ir # Works like git rebase -ir @{upstream}
>   git push --force origin main:a
>   git rebase -ir # No longer works like git rebase -ir @{upstream}

This works fine here.

-- 
Felipe Contreras