[PATCH v2] diff-no-index: exit(1) if 'diff --quiet <repo file> <external file>' finds changes

[Tim Henigan <tim.henigan@gmail.com>]

When running 'git diff --quiet <file1> <file2>', if file1 or file2
is outside the repository, it will exit(0) even if the files differ.
It should exit(1) when they differ.

Signed-off-by: Tim Henigan <tim.henigan@gmail.com>
---

Changes in v2:
  - Implemented the fix in diff-no-index.c as suggested by Junio
    Hamano.  The previous version affected the performance of all
    diff commands that used the '--quiet' option by forcing the
    code through the expensive (and in this case unneccesary)
    'diff_flush_patch' code path.
  - Updated the test to use 'test_expect_code' as suggested by
    Jeff King.


 diff-no-index.c       | 3 ++-
 t/t4035-diff-quiet.sh | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/diff-no-index.c b/diff-no-index.c
index f0b0010..b935d2a 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -273,5 +273,6 @@ void diff_no_index(struct rev_info *revs,
 	 * The return code for --no-index imitates diff(1):
 	 * 0 = no changes, 1 = changes, else error
 	 */
-	exit(revs->diffopt.found_changes);
+	int result = diff_result_code(&revs->diffopt, 0);
+	exit(result);
 }
diff --git a/t/t4035-diff-quiet.sh b/t/t4035-diff-quiet.sh
index cdb9202..0b83235 100755
--- a/t/t4035-diff-quiet.sh
+++ b/t/t4035-diff-quiet.sh
@@ -76,4 +77,8 @@ test_expect_success 'git diff-index --cached HEAD' '
 	}
 '
 
+test_expect_success 'git diff <tracked file> <file outside repo>' '
+	test_expect_code 1 git diff --quiet c /dev/null
+'
+
 test_done
-- 
1.7.11.rc3.6.g894ec42.dirty