[PATCH] stash: copy the index using --index-output instead of cp -p

[Johannes Sixt <j.sixt@viscovery.net>]

From: Johannes Sixt <j6t@kdbg.org>

'git stash create' must operate with a temporary index. For this purpose,
it used 'cp -p' to create a copy. -p is needed to preserve the timestamp
of the index file. Now Jakob Pfender reported a certain combination of
a Linux NFS client, OpenBSD NFS server, and cp implementation where this
operation failed.

Luckily, the first operation in git-stash after copying the index is to
call 'git read-tree'. Therefore, use --index-output instead of 'cp -p'
to write the copy of the index.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Tested-by: Jakob Pfender <jpfender@elegosoft.com>
---
 Here's a wrap-up. Acked-by is reserved for people whose area-of-expertise
 is touched by someone else. Tested-by is more appropriate here.

 git-stash.sh |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/git-stash.sh b/git-stash.sh
index 7561b37..fa62135 100755
--- a/git-stash.sh
+++ b/git-stash.sh
@@ -82,10 +82,9 @@ create_stash () {
 		# state of the working tree
 		w_tree=$( (
 			rm -f "$TMP-index" &&
-			cp -p ${GIT_INDEX_FILE-"$GIT_DIR/index"} "$TMP-index" &&
+			git read-tree --index-output="$TMP-index" -m $i_tree &&
 			GIT_INDEX_FILE="$TMP-index" &&
 			export GIT_INDEX_FILE &&
-			git read-tree -m $i_tree &&
 			git diff --name-only -z HEAD | git update-index -z --add --remove --stdin &&
 			git write-tree &&
 			rm -f "$TMP-index"
-- 
1.7.4.rc3.76.gfb457d