fetch-object: set exact_oid when fetching

fetch_objects() currently does not set exact_oid in struct ref when
invoking transport_fetch_refs(). If the server supports ref-in-want,
fetch_pack() uses this field to determine whether a wanted ref should be
requested as a "want-ref" line or a "want" line; without the setting of
exact_oid, the wrong line will be sent.

Set exact_oid, so that the correct line is sent.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch-object.c

@@ -32,6 +32,7 @@ void fetch_objects(const char *remote_name, const struct object_id *oids,
 	for (i = 0; i < oid_nr; i++) {
 		struct ref *new_ref = alloc_ref(oid_to_hex(&oids[i]));
 		oidcpy(&new_ref->old_oid, &oids[i]);
+		new_ref->exact_oid = 1;
 		new_ref->next = ref;
 		ref = new_ref;
 	}

t/t0410-partial-clone.sh

@@ -170,6 +170,18 @@ test_expect_success 'fetching of missing objects' '
 	git verify-pack --verbose "$IDX" | grep "$HASH"
 '
 
+test_expect_success 'fetching of missing objects works with ref-in-want enabled' '
+	# ref-in-want requires protocol version 2
+	git -C server config protocol.version 2 &&
+	git -C server config uploadpack.allowrefinwant 1 &&
+	git -C repo config protocol.version 2 &&
+
+	rm -rf repo/.git/objects/* &&
+	rm -f trace &&
+	GIT_TRACE_PACKET="$(pwd)/trace" git -C repo cat-file -p "$HASH" &&
+	grep "git< fetch=.*ref-in-want" trace
+'
+
 test_expect_success 'rev-list stops traversal at missing and promised commit' '
 	rm -rf repo &&
 	test_create_repo repo &&