From: Jeff King <peff@peff.net>
Date: Sat, 22 Mar 2008 16:57:37 GMT
Subject: Re: How to rewrite author history
Message-ID: <20080322165737.GB7611@coredump.intra.peff.net>
In-Reply-To: <216e54900803220611v5aa5e9d5q86da249480be3c91@mail.gmail.com>

On Sat, Mar 22, 2008 at 06:11:12AM -0700, Andrew Arnott wrote:

> git-filter-branch --env-filter '
> [...]
> And I did this for master, and my v1 and v0.1 branches.  I'm concerned
> though, that since I changed the names of all the objects by doing
> this, did I somehow make my branches incompatible with each other?
> Will there be any problems in the future sharing commits or merging
> across branches as a result?

There are two concerns, and I'm not sure which you have (I think number
1):

  1. Your branches within the repository will not connect anymore. I
     believe this is a non-issue with your filter, since the generated
     commit IDs are deterministic. Certainly a toy case worked for me
     with:

       for i in master branch; do
         git filter-branch --env-filter=... $i
       done

     You can also specify both to be done at the same time, which is
     more efficient:

       git filter-branch --env-filter=... master branch

     You can check the graph structure with "gitk master branch" which
     should show them connecting.

  2. Your branches are now a different, rewritten history compared to
     anyone who has cloned or fetched from you. This is unavoidable, and
     the answer is either "don't use filter-branch" or "tell everyone to
     rebase their work on the new history." So the best time to
     filter-branch is right after import, but before you start work.

-Peff