git stash: show status relative to current directory

git stash: show status relative to current directory

git status shows modified paths relative to current directory, so it's
possible to copy&paste them directly, even if you're in a subdirectory.

But "git stash apply" always shows status from root of git repository.
This is misleading because you can't use the paths without modifications.

This is caused by changing directory to root of repository at the
beginning of git stash.

This patch makes git stash show status relative to current directory.
Instead of removing the "cd to toplevel", which would affect whole
script and might have other side-effects, the fix is to change directory
temporarily back to original dir just before displaying status.

Signed-off-by: Piotr Krukowiecki <piotr.krukowiecki@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>