Re: Master and origin/master diverged

From: Neal Kreitzinger <nkreitzinger@gmail.com>
Date: Jun 22, 2012, 23:47 UTC
Message-ID: <4FE50411.8080800@gmail.com>
In-Reply-To: <CAE1pOi2MN_c76UBeRzdRbU8s+0LzYVoVcJ13V0di=HQobj+aDg@mail.gmail.com>

On 6/22/2012 3:18 PM, Hilco Wijbenga wrote:

Show 27 quoted lines

>
> On 22 June 2012 12:01, Neal Kreitzinger <nkreitzinger@gmail.com> wrote:
>> On 6/22/2012 12:53 PM, Hilco Wijbenga wrote:
>>>
>>> One of my developers managed to push something that somehow "diverged"
>>> origin/master from everyone else's local master.
>>>
>>> A --> B --> C --> D (everybody's local master)
>>> |
>>> \--> B' --> C' --> D' --> E (origin/master)
>>>
>>> (i.e., A is the commit where things diverged; everyone's local master
>>> points to D but the new commit (E) that was pushed to origin/master
>>> uses different SHA1s for B, C, and D)...
>>>
>>> Now running git pull creates a merge commit joining D and E.
>>>
>>> ...Does anyone have any idea as to what might have happened? Perhaps if I
>>> understand how this happened I might be able to prevent it from
>>> happening again.
>>>
>> Some ways you can prevent it from happening again:
>
>> (2) have your devs do git pull --ff-only
>
> Is this something that can be set in git config? I looked but didn't
> see anything obvious.

OTTOMH, you could change the git fetch config for master and take away the leading '+' sign which would not allow non-fastforward fetches of master. That in turn would prevent merging such a non-ff remote tracking branch of master into your branch master.

Actually, I guess what I really want is

> something for git push, right?
>

Some ways to do it: (1) I think you could have rebase and commit hooks locally that prevent someone from rewriting history on master. That in turn would prevent someone from pushing a rewritten history. (2) When merging topic branches to master use git merge --ff-only. Then when you push it to remote master you know it's a fastforward and not a history rewrite.

v/r, neal