Subject: Bugs in git filter-branch (git replace related)

From: Anatoly Borodin <[email-masked]>
Date: Thu, 28 Jan 2016 14:46:40 +0000 (UTC)

Hi All!

There are two bugs in `git filter-branch`, present in the most recent
versions (d10e2cb9d0299a26f43d57dd5bdcf2b3f86a30b3), as well as in the old
ones (I couldn't find a version where it works properly).

The script:

#!/bin/sh

set -e

GIT_EXEC_PATH=/tmp/git
export GIT_EXEC_PATH
GIT=$GIT_EXEC_PATH/git

rm -rf a
mkdir a
cd a
$GIT init
echo aaa > a.txt && $GIT add a.txt && $GIT commit -a -m a
echo bbb > a.txt && $GIT add a.txt && $GIT commit -a -m b
echo ccc > a.txt && $GIT add a.txt && $GIT commit -a -m c
$GIT replace f761ec192d9f0dca3329044b96ebdb12839dbff6
72943a16fb2c8f38f9dde202b7a70ccc19c52f34
echo && echo One && $GIT filter-branch --prune-empty -- master
echo && echo Two && $GIT filter-branch --prune-empty -- --all

The output is:

...
One
Rewrite 98af0305b778bf56e25a0d4f85acdf82f435f9b3 (3/3) (0 seconds passed,
remaining 0 predicted)    
WARNING: Ref 'refs/heads/master' is unchanged

Two
Rewrite 98af0305b778bf56e25a0d4f85acdf82f435f9b3 (3/3) (0 seconds passed,
remaining 0 predicted)    
WARNING: Ref 'refs/heads/master' is unchanged
error: object 72943a16fb2c8f38f9dde202b7a70ccc19c52f34 is a blob, not a commit
error: object 72943a16fb2c8f38f9dde202b7a70ccc19c52f34 is a blob, not a commit
fatal: ambiguous argument
'refs/replace/f761ec192d9f0dca3329044b96ebdb12839dbff6^0': unknown revision
or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
WARNING: Ref 'refs/replace/f761ec192d9f0dca3329044b96ebdb12839dbff6' is
unchanged

The `git replace` makes the second commit empty (use the file content from
the first commit). It should disappear after `git filter-branch`, but it
doesn't happen.

Bug 1: the empty commit stays.
Bug 2: the replace refs are not ignored (they can epresent blobs, trees etc,
but even if they represent commits - should they be rewritten?).

Any ideas?

PS I've found http://article.gmane.org/gmane.comp.version-control.git/220931
, seems like the bug 1. But it's old!