[PATCH] Cleanup: git-verify-tag-script

- Use git-rev-parse to allow sha1 tags references
- When the tag does not verify set an appropriate exit status
- Use git-sh-setup-script to verify the .git directory
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

git-verify-tag-script

 #!/bin/sh
-GIT_DIR=${GIT_DIR:-.git}
+. git-sh-setup-script || die "Not a git archive"
 
-tag=$1
-[ -f "$GIT_DIR/refs/tags/$tag" ] && tag=$(cat "$GIT_DIR/refs/tags/$tag")
+tag=$(git-rev-parse $1) || exit 1
 
 git-cat-file tag $tag > .tmp-vtag || exit 1
-cat .tmp-vtag | sed '/-----BEGIN PGP/Q' | gpg --verify .tmp-vtag -
+cat .tmp-vtag | sed '/-----BEGIN PGP/Q' | gpg --verify .tmp-vtag - || exit 1
 rm -f .tmp-vtag