Re: Dangers of working on a tracking branch

From: Jakub Narebski <jnareb@gmail.com>
Date: Feb 16, 2007, 02:00 UTC
Message-ID: <er333i$787$1@sea.gmane.org>
In-Reply-To: <17876.53654.426022.454712@lisa.zopyra.com>

Bill Lear wrote:

Show 17 quoted lines

> On Thursday, February 15, 2007 at 15:21:38 (-0600) Bill Lear writes:
>>On Thursday, February 15, 2007 at 16:00:23 (-0500) Nicolas Pitre writes:
>>>On Thu, 15 Feb 2007, Bill Lear wrote:
>>>
>>>> We are about to switch to git 1.5 from git 1.4.4.1.  I cannot remember
>>>> if someone posted about this, but what is the danger of working on a
>>>> tracking branch --- there are abundant cautions about doing this, but
>>>> I can't recall and can't find the reason this is bad.
>>>
>>>A tracking branch is supposed to be a local mirror of what is available 
>>>remotely.  If you commit local changes to it then you break that model.
>>
>>Ok, so I break the model, what is the harm in that?  Can I no longer
>>pull from or push to the remote branch?  Do I corrupt something
>>locally?  Does something else break?  I'm trying to formulate an
>>explanation to our users why the 1.5 way is superior and I can't just
>>say "if you do that you break the model".

You cannot fetch or push to the remote branch if you made some commits on the tracking branch ("broke the model") and remote branch has other commits. You can force the issue, but then either remote (for push) or local (for fetch) commits would be lost.

Sidenote: for some branches you have to skip fast-forward check, because
they have rewritten history (e.g. pu branch in git.git).

> BTW, my ignorant assumption is that for merging to take place, git
> requires two branches, so 'git pull' will fetch into the tracking
> branch and then merge onto your ... uh ... whatever the name of the
> working version of your tracking branch is.

But one of those branches can be temporary "branch" FETCH_HEAD (if you use "git pull <URL>" syntax, and do not use tracking (remote) branches).

> BTW, again, why does git clone not have an option to just create all
> of the "working versions" (better name needed) of tracking branches?

Because usually you work with one branch with tracking (remote) + local branch workflow; I think with multiple branches you usually use temporary feature branches...

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git