Re: How does git store branchpoints?

From: Jakub Narebski <jnareb@gmail.com>
Date: Jun 9, 2008, 20:53 UTC
Message-ID: <m38wxewcno.fsf@localhost.localdomain>
In-Reply-To: <fd42f577-60ba-4d26-85a3-7ca4ea8295db@a1g2000hsb.googlegroups.com>

davetron5000 <davetron5000@gmail.com> writes:

Show 9 quoted lines

> >
> > You can ask git to find branch point using "git merge-base trunk FOO",
> > which should return 'c' (actually, sha-1 of this commit).
> 
> OK, this revealed interesting results.  The commit it gave me was a
> commit right before ANOTHER SVN branch that I was originally to work
> on, but never did.  The files git-merge showed conflicts for were
> files modified since THAT branch (call it BAR) was created and before
> my branch (FOO) was created.

Could you write some ascii-art diagram showing the situation? It is
hard to grasp the situation fully only from above description.

> So, any ideas why git thinks that my two branches are rooted at BAR
> and not FOO?  git-svn dcommit on local-FOO commits to FOO and not BAR.

Note that the situation described below might be not related to your problem; please view history carefully using some (graphical) history browser like gitk.

It could happen that commits which should be identical aren't, e.g. because of different timestamp, or different author, or lack of svn-id: line, or something like that. This isn't helped by the fact that Subversion doesn't store information about merges; and even if it does (SVK or svnmerge extensions) I'm not sure if git-svn can use it.

So the situation might be like following:

   1---2---3---4---A---B---C   <-- branch 1

   1'--2'--3'--4'--a---b---c   <-- branch 2

while you want it to be

   1---2---3---4---A---B---C   <-- branch 1
                \
                 \-a---b---c   <-- branch 2

Usually working with grafts, examining result in gitk, then commiting grafts using git-filter-branch is the solution for such history rewriting.

-- 
Jakub Narebski
Poland
ShadeHawk on #git