[PATCH 7/9] ref-filter: make %(upstream:track) prints "[gone]" for invalid upstreams

[Karthik Nayak <karthik.188@gmail.com>]

Borrowing from branch.c's implementation print "[gone]" whenever an
unknown upstream ref is encountered instead of just ignoring it.

This makes sure that when branch.c is ported over to using ref-filter
APIs for printing, this feature is not lost.

Make changes to t/t6300-for-each-ref.sh to reflect this change.

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
---
 ref-filter.c            | 4 +++-
 t/t6300-for-each-ref.sh | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/ref-filter.c b/ref-filter.c
index 099acd6..48b06e3 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1133,8 +1133,10 @@ static void populate_value(struct ref_array_item *ref)
 				char buf[40];
 
 				if (stat_tracking_info(branch, &num_ours,
-						       &num_theirs, NULL))
+						       &num_theirs, NULL)) {
+					v->s = xstrdup("[gone]");
 					continue;
+				}
 
 				if (!num_ours && !num_theirs)
 					v->s = "";
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 7f675d2..2a01645 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -359,7 +359,7 @@ test_expect_success 'Check that :track[short] cannot be used with other atoms' '
 
 test_expect_success 'Check that :track[short] works when upstream is invalid' '
 	cat >expected <<-\EOF &&
-
+	[gone]
 
 	EOF
 	test_when_finished "git config branch.master.merge refs/heads/master" &&
-- 
2.6.0