[PATCH v2] apply: make --intent-to-add not stomp index

[Johannes Altmanninger <aclopte@gmail.com>]

Commit cff5dc09ed (apply: add --intent-to-add, 2018-05-26) introduced
"apply -N" plus a test to make sure it behaves exactly as "add -N"
when given equivalent changes.  However, the test only checks working
tree changes. Now "apply -N" forgot to read the index, so it left
all tracked files as deleted, except for the ones it touched.

Fix this by reading the index file, like we do for "apply --cached".
and test that we leave no content changes in the index.

Reported-by: Ryan Hodges <rhodges@cisco.com>
Signed-off-by: Johannes Altmanninger <aclopte@gmail.com>
---

Sorry I used the wrong Reported-by: address in v1

 apply.c               | 2 +-
 t/t2203-add-intent.sh | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/apply.c b/apply.c
index 43a0aebf4e..4f740e373b 100644
--- a/apply.c
+++ b/apply.c
@@ -4771,7 +4771,7 @@ static int apply_patch(struct apply_state *state,
 					       LOCK_DIE_ON_ERROR);
 	}
 
-	if (state->check_index && read_apply_cache(state) < 0) {
+	if ((state->check_index || state->ita_only) && read_apply_cache(state) < 0) {
 		error(_("unable to read index file"));
 		res = -128;
 		goto end;
diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
index cf0175ad6e..035ce3a2b9 100755
--- a/t/t2203-add-intent.sh
+++ b/t/t2203-add-intent.sh
@@ -307,7 +307,7 @@ test_expect_success 'apply --intent-to-add' '
 	grep "new file" expected &&
 	git reset --hard &&
 	git apply --intent-to-add expected &&
-	git diff >actual &&
+	(git diff && git diff --cached) >actual &&
 	test_cmp expected actual
 '
 
-- 
2.33.1