t3030-merge-recursive: test known breakage with empty work tree
authorBrad King <brad.king@kitware.com>
Mon, 27 Jan 2014 14:45:06 +0000 (09:45 -0500)
committerJunio C Hamano <gitster@pobox.com>
Mon, 24 Feb 2014 22:30:22 +0000 (14:30 -0800)
Sometimes when working with a large repository it can be useful to try
out a merge and only check out conflicting files to disk (for example as
a speed optimization on a server). Until v1.7.7-rc1~28^2~20
(merge-recursive: When we detect we can skip an update, actually skip
it, 2011-08-11), it was possible to do so with the following idiom:

# Prepare a temporary index and empty work tree.
GIT_INDEX_FILE="$PWD/tmp-$$-index" &&
export GIT_INDEX_FILE &&
GIT_WORK_TREE="$PWD/tmp-$$-work" &&
export GIT_WORK_TREE &&
mkdir "$GIT_WORK_TREE" &&

# Convince the index that our side is on disk.
git read-tree -i -m $ours &&
git update-index --ignore-missing --refresh &&

# Merge their side into our side.
bases=$(git merge-base --all $ours $theirs) &&
git merge-recursive $bases -- $ours $theirs &&
tree=$(git write-tree)

Nowadays, that still works and the exit status is the same, but
merge-recursive produces a diagnostic if "our" side renamed a file:

error: addinfo_cache failed for path 'dst'

Add a test to document this regression.

Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
No differences found