Audit rev-parse users.

Make sure that we say --verify when we want to get a single SHA1
name.  Also when we say --verify, --revs-only is redundant.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/git-tag-script b/git-tag-script
index d3074a8..39c3c53 100755
--- a/git-tag-script
+++ b/git-tag-script
@@ -47,7 +47,7 @@
 fi
 shift
 
-object=$(git-rev-parse --verify --revs-only --default HEAD "$@") || exit 1
+object=$(git-rev-parse --verify --default HEAD "$@") || exit 1
 type=$(git-cat-file -t $object) || exit 1
 tagger=$(git-var GIT_COMMITTER_IDENT) || exit 1