[PATCH 06/15] 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 2896cde..c8ba68f 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -1039,8 +1039,10 @@ static void fill_remote_ref_details(struct used_atom *atom, const char *refname,
 		*s = shorten_unambiguous_ref(refname, warn_ambiguous_refs);
 	else if (atom->u.remote_ref == RR_TRACK) {
 		if (stat_tracking_info(branch, &num_ours,
-				       &num_theirs, NULL))
+				       &num_theirs, NULL)) {
+			*s = "[gone]";
 			return;
+		}
 
 		if (!num_ours && !num_theirs)
 			*s = "";
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 2be0a3f..a92b36f 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -382,7 +382,7 @@ 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" &&
-- 
2.7.2