Git help: amending a substandard commit message in savannah.

Git help: amending a substandard commit message in savannah.

[Alan Mackenzie]

Hello, Emacs.

Yesterday, I committed a fix to savannah on "my own" branch
fix/not-defined-at-runtime.  The commit message was poorly constructed.

I have corrected this locally with

    git commit --amend

.  When I attempt to push this to savannah with

    git push --force

, my attempt quite properly gets rejected with an error message.

Is there any way I can get this correction onto this branch (e.g. does
anybody have the necessary permissions to perform the git push --force),
or would I be better just to abandon the branch and create another one?

By the way, what happens to abandoned branches?  Does anybody do a
periodic scan of branches to get rid of them?  They surely don't go away
of their own accord.  If they aren't garbage collected, then the
repository's list of branches will steadily fill up with useless cruft.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Git help: amending a substandard commit message in savannah.

[David Caldwell]

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On 11/23/15 2:51 AM, Alan Mackenzie wrote:
> By the way, what happens to abandoned branches?  Does anybody do a
> periodic scan of branches to get rid of them?  They surely don't go away
> of their own accord.  If they aren't garbage collected, then the
> repository's list of branches will steadily fill up with useless cruft.

I'm not sure about Savannah, but generally with git you can delete
remote branches with this syntax:

   git push origin :branch_to_be_deleted

If that is allowed, then deleting that branch and then pushing it back
with your amended change would effectively be the same as `git push -f`.

-David



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Re: Git help: amending a substandard commit message in savannah.

[David Kastrup]

David Caldwell <david@porkrind.org> writes:

> On 11/23/15 2:51 AM, Alan Mackenzie wrote:
>> By the way, what happens to abandoned branches?  Does anybody do a
>> periodic scan of branches to get rid of them?  They surely don't go away
>> of their own accord.  If they aren't garbage collected, then the
>> repository's list of branches will steadily fill up with useless cruft.
>
> I'm not sure about Savannah, but generally with git you can delete
> remote branches with this syntax:
>
>    git push origin :branch_to_be_deleted
>
> If that is allowed, then deleting that branch and then pushing it back
> with your amended change would effectively be the same as `git push -f`.

You glossed over one detail.  The problem is when pushing to an
_existing_ branch, Git uses the existence of the branch to deduce that
you actually want the reference to be refs/heads/branch_to_be_deleted .
So you can use

    git push origin :branch_to_be_deleted

in order to delete the branch, but once it is gone, you need to do

    git push origin HEAD:refs/heads/branch_to_be_deleted

in order to recreate it (after which it is again possible to refer to it
using just branch_to_be_deleted).  So in order to avoid typos, it's
better to delete it with

    git push origin :refs/heads/branch_to_be_deleted

which sort-of makes sure that you are recreating the same branch when
editing the command line in order to insert HEAD or whatever.

Because a reference actually called branch_to_be_deleted (without
starting refs/heads/) is a nuisance to get rid of again and is not
recognized as a branch by branch-specific commands.

-- 
David Kastrup

Re: Git help: amending a substandard commit message in savannah.

[Yuri Khan]

On Mon, Nov 23, 2015 at 5:32 PM, David Kastrup <dak@gnu.org> wrote:

> So you can use
>
>     git push origin :branch_to_be_deleted
>
> in order to delete the branch, but once it is gone, you need to do
>
>     git push origin HEAD:refs/heads/branch_to_be_deleted
>
> in order to recreate it

Not necessarily. You can say

    git push origin my_branch

and it will be pushed to origin as refs/heads/my_branch.

Also, my quick experiment shows that all these commands create
branches in the origin under refs/heads/:

    git push origin my_branch
    git push origin my_branch:other_branch
    git push origin HEAD:more_branch

Can this be a Git version difference? I’m on 2.6.3.

Re: Git help: amending a substandard commit message in savannah.

[David Caldwell]

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On 11/23/15 3:32 AM, David Kastrup wrote:
> David Caldwell <david@porkrind.org> writes:
> 
>> On 11/23/15 2:51 AM, Alan Mackenzie wrote:
>>> By the way, what happens to abandoned branches?  Does anybody do a
>>> periodic scan of branches to get rid of them?  They surely don't go away
>>> of their own accord.  If they aren't garbage collected, then the
>>> repository's list of branches will steadily fill up with useless cruft.
>>
>> I'm not sure about Savannah, but generally with git you can delete
>> remote branches with this syntax:
>>
>>    git push origin :branch_to_be_deleted
>>
>> If that is allowed, then deleting that branch and then pushing it back
>> with your amended change would effectively be the same as `git push -f`.
> 
> You glossed over one detail.  The problem is when pushing to an
> _existing_ branch, Git uses the existence of the branch to deduce that
> you actually want the reference to be refs/heads/branch_to_be_deleted .
> So you can use
> 
>     git push origin :branch_to_be_deleted
> 
> in order to delete the branch, but once it is gone, you need to do
> 
>     git push origin HEAD:refs/heads/branch_to_be_deleted
> 
> in order to recreate it (after which it is again possible to refer to it
> using just branch_to_be_deleted).

Er, what? That's not right. Once you've deleted a branch on the remote
git server you can just push it back using whatever command you created
it with in the first place. Of course the commands you gave will work,
but it's over-complicating things certainly not required. You can do
this all day:

    git push origin :branch_to_be_deleted
    git push origin branch_to_be_deleted
    git push origin :branch_to_be_deleted
    git push origin branch_to_be_deleted
    git push origin :branch_to_be_deleted
    git push origin branch_to_be_deleted
 …etc.

It's easy enough to test:

    cd /tmp
    mkdir test
    cd test
    mkdir a
    cd a
    git init
    echo a > a
    git add a
    git commit -m a
    cd ..
    git clone a b
    cd b
    git checkout -b mybranch
    echo b > b
    git add b
    git commit -m b
    git push origin mybranch
    git push origin :mybranch
    git push origin mybranch
    git push origin :mybranch
    git push origin mybranch

-David



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Re: Git help: amending a substandard commit message in savannah.

[David Kastrup]

David Caldwell <david@porkrind.org> writes:

> On 11/23/15 3:32 AM, David Kastrup wrote:
>
>> So you can use
>> 
>>     git push origin :branch_to_be_deleted
>> 
>> in order to delete the branch, but once it is gone, you need to do
>> 
>>     git push origin HEAD:refs/heads/branch_to_be_deleted
>> 
>> in order to recreate it (after which it is again possible to refer to it
>> using just branch_to_be_deleted).
>
> Er, what? That's not right. Once you've deleted a branch on the remote
> git server you can just push it back using whatever command you created
> it with in the first place. Of course the commands you gave will work,
> but it's over-complicating things certainly not required. You can do
> this all day:
>
>     git push origin :branch_to_be_deleted
>     git push origin branch_to_be_deleted

_Iff_ the reference you push has the name branch_to_be_deleted in the
first place.  If you name the reference explicitly, namely if your
pushing command contains a : sign, then you need the full reference name
on the right side of the :.  If you only name one reference, then the
disambiguation used for finding the reference in the local repository
will be pushed to the remote side.

Try

    git push origin HEAD:branch_to_be_deleted

to see what I mean.  Or even

    git push origin branch_to_be_deleted:branch_to_be_deleted

-- 
David Kastrup

Re: Git help: amending a substandard commit message in savannah.

[Artur Malabarba]

> .  When I attempt to push this to savannah with
>
>     git push --force
>
> , my attempt quite properly gets rejected with an error message.

Are you sure that message wasn't because you inadvertently tried force
pushing to master? I think older git versions default to pushing
everything if you don't specify branches.
I'm asking this because I'm relatively certain I've force pushed to
scratch branches in the past without issues.

Re: Git help: amending a substandard commit message in savannah.

[Eli Zaretskii]

> Date: Mon, 23 Nov 2015 10:51:52 +0000
> From: Alan Mackenzie <acm@muc.de>
> 
> I have corrected this locally with
> 
>     git commit --amend
> 
> .  When I attempt to push this to savannah with
> 
>     git push --force
> 
> , my attempt quite properly gets rejected with an error message.
> 
> Is there any way I can get this correction onto this branch (e.g. does
> anybody have the necessary permissions to perform the git push --force),

Only Savannah admins can do that.

> or would I be better just to abandon the branch and create another one?

You shouldn't worry about this at all, since you will get a second
chance when you merge/rebase this branch onto master.  Be sure to
double-check your log message at that time before you push, and Bob's
your uncle.

Re: Git help: amending a substandard commit message in savannah.

[Alan Mackenzie]

Hello, Eli.

On Mon, Nov 23, 2015 at 06:21:12PM +0200, Eli Zaretskii wrote:
> > Date: Mon, 23 Nov 2015 10:51:52 +0000
> > From: Alan Mackenzie <acm@muc.de>
> > 
> > I have corrected this locally with
> > 
> >     git commit --amend
> > 
> > .  When I attempt to push this to savannah with
> > 
> >     git push --force
> > 
> > , my attempt quite properly gets rejected with an error message.
> > 
> > Is there any way I can get this correction onto this branch (e.g. does
> > anybody have the necessary permissions to perform the git push --force),

> Only Savannah admins can do that.

Which makes sense.

> > or would I be better just to abandon the branch and create another one?

> You shouldn't worry about this at all, since you will get a second
> chance when you merge/rebase this branch onto master.  Be sure to
> double-check your log message at that time before you push, and Bob's
> your uncle.

Ah.  Thanks a lot for this!  So when the time comes I'll be careful
about these messages.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Git help: amending a substandard commit message in savannah.

[John Yates]

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> From: Alan Mackenzie <acm@muc.de>
> or would I be better just to abandon the branch and create another one?

My understanding is that if you never merge that tip with its sub-par
commit message into master then ultimately it will time out and get garbage
collected.  You could create a new branch just before the one you wish to
amend and push that new branch to Savannah.  (Under the covers that is more
or less what git amend does.)  From then on you would work on that new
branch, ultimately merging it into master.

/john

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Re: Git help: amending a substandard commit message in savannah.

[Alan Mackenzie]

Hello, John

On Mon, Nov 23, 2015 at 11:42:49AM -0500, John Yates wrote:
> > From: Alan Mackenzie <acm@muc.de>
> > or would I be better just to abandon the branch and create another one?

> My understanding is that if you never merge that tip with its sub-par
> commit message into master then ultimately it will time out and get
> garbage collected.  You could create a new branch just before the one
> you wish to amend and push that new branch to Savannah.  (Under the
> covers that is more or less what git amend does.)  From then on you
> would work on that new branch, ultimately merging it into master.

Presumably the timeout period is some system-wide setting, and it will
be something like 3 months.

> /john

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: Git help: amending a substandard commit message in savannah.

[David Kastrup]

Alan Mackenzie <acm@muc.de> writes:

> Hello, John
>
> On Mon, Nov 23, 2015 at 11:42:49AM -0500, John Yates wrote:
>> > From: Alan Mackenzie <acm@muc.de>
>> > or would I be better just to abandon the branch and create another one?
>
>> My understanding is that if you never merge that tip with its sub-par
>> commit message into master then ultimately it will time out and get
>> garbage collected.  You could create a new branch just before the one
>> you wish to amend and push that new branch to Savannah.  (Under the
>> covers that is more or less what git amend does.)  From then on you
>> would work on that new branch, ultimately merging it into master.
>
> Presumably the timeout period is some system-wide setting, and it will
> be something like 3 months.

You can _delete_ the branch and push a "new" branch with the same name
right away.

I do that frequently for temporary branches in a repository that does
not allow forced rewrites.

The timeouts are for cleaning out commits that are no longer referenced
in a branch or tag.  Those commits remain accessible by commit id in the
repository for three months before they are cleaned out when they are
not accessible through a symbolic reference like an actual branch or
tag.

-- 
David Kastrup