Re: Master and origin/master diverged

[Neal Kreitzinger <nkreitzinger@gmail.com>]

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