[PATCH] require_work_tree broken with NONGIT_OK

When sourcing git-sh-setup after having set NONGIT_OK, calling the
function require_work_tree while outside of a git repository shows a
syntax error.

This is caused by the call to "git rev-parse --is-inside-work-tree"
printing a sentence when it is called outside of a git repository.
Relying on the return code is better.
---
 git-sh-setup.sh |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/git-sh-setup.sh b/git-sh-setup.sh
index d56426d..8de2f03 100755
--- a/git-sh-setup.sh
+++ b/git-sh-setup.sh

@@ -128,7 +128,7 @@ cd_to_toplevel () {
 }
  require_work_tree () {
-	test $(git rev-parse --is-inside-work-tree) = true ||
+	test git rev-parse --is-inside-work-tree >/dev/null 2>&1 ||
 	die "fatal: $0 cannot be used without a working tree."
 }
 -- 1.6.6