From: Elijah Newren <newren@gmail.com>
Date: Fri, 23 Aug 2019 18:29:14 GMT
Subject: Re: RFC: Proposing git-filter-repo for inclusion in git.git
Message-ID: <CABPp-BFxOA83uL=gsNir5zSgMsfBX6=9+YnWqp+Q4NiztiC6bw@mail.gmail.com>
In-Reply-To: <CABPp-BEDOH-row-hxY4u_cP30ptqOpcCvPibwyZ2wBu142qUbA@mail.gmail.com>

On Fri, Aug 23, 2019 at 11:06 AM Elijah Newren <newren@gmail.com> wrote:
<snip>
> Safety:
<snip>

Ooh, and another one I remembered just after hitting 'send':
  * If the user provides a --tag-name-filter that maps multiple tags
to the same name, no warning or error is provided; filter-branch
simply overwrites each tag in some undocumented pre-defined order
(lexicographic) resulting in only one tag at the end.  A regression
test will fail if you attempt to error out and warn the user, so if
you are trying to make a backward compatible reimplementation you have
to add extra code to detect collisions and make sure that only the
lexicographically last one is rewritten.  (fast-import will naturally
error out if told to write the same tag more than once, so you have to
avoid triggering it.)

<snip>
> Summary of above: Anything compatible with git-filter-branch will be
> slower than molasses and extraordinarily unsafe.
<snip.