From: Jon Seymour <jon.seymour@gmail.com>
Date: Wed, 13 Jan 2010 17:14:26 GMT
Subject: Re: discussion: an option to fail git fetch if a pulled branch tip is not a fast forward of the existing remote tip?
Message-ID: <230F8BFF-7F59-47DB-9E97-D8E081D2597B@gmail.com>
In-Reply-To: <201001131359.09613.trast@student.ethz.ch>

Thomas,

Ah - thanks for your very helpful response!

jon.

On 13/01/2010, at 23:59, Thomas Rast <trast@student.ethz.ch> wrote:

> Jon Seymour wrote:
> [discussion of a case of branch rewriting, called "backtracking" here]
>> Now clearly the upstream developer should not have backtracked. That
>> said, it would have been nice if I could have easily configured my
>> porcelain to detect the backtracking condition. An option on git  
>> fetch
>> that implemented something similar to the git push check would have
>> made this easy to achieve.
>
> This is an instance of a non-fast-foward update, which is indicated by
> the little "+" in git-fetch's output.  E.g., fetching git.git a moment
> ago gave me
>
> From git://git.kernel.org/pub/scm/git/git
>   fbb9971..8efa5f6  maint      -> origin/maint
>   c0eb604..054d2fa  master     -> origin/master
>   e295b7f..e84eab0  next       -> origin/next
> + 10659b7...6a048fc pu         -> origin/pu  (forced update)
>
> which means that the 'pu' branch was a non-fast-forward update.
>
> If you do not want to rely on checking the results manually, you can
> edit the remote configuration.  Normally, it will look like
>
> [remote "origin"]
>        url = git://git.kernel.org/pub/scm/git/git.git
>        fetch = +refs/heads/*:refs/remotes/origin/*
>
> Note the "+" in the 'fetch' line, which means "allow non-fast-forward
> updates".  Removing the + (leaving the rest intact) results in
>
> From git://git.kernel.org/pub/scm/git/git
> ! [rejected]        pu         -> origin/pu  (non-fast-forward)
>
> You can then manually add lines _with_ the "+" for branches where you
> do want to allow non-ff updates, e.g., for git.git I might say
>
> [remote "origin"]
>        url = git://git.kernel.org/pub/scm/git/git.git
>        fetch = +refs/heads/pu:refs/remotes/origin/pu
>        fetch = refs/heads/*:refs/remotes/origin/*
>
> since only 'pu' will be rewritten regularly. ('next' gets the
> occasional treatment too, so that config would not be very
> futureproof.)
>
> -- 
> Thomas Rast
> trast@{inf,student}.ethz.ch