[PATCH] send-pack: Filter unknown commits from alternates of the remote

["Björn Steinbrink" <B.Steinbrink@gmx.de>]

Since 40c155ff14c, receive-pack on the remote also sends refs from its
alternates. Unfortunately, we don't filter commits that don't exist in the
local repository from that list.  This made us pass those unknown commits
to pack-objects, causing it to fail with a "bad object" error.

Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
---
 builtin-send-pack.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/builtin-send-pack.c b/builtin-send-pack.c
index a9fdbf9..10d7016 100644
--- a/builtin-send-pack.c
+++ b/builtin-send-pack.c
@@ -52,11 +52,15 @@ static int pack_objects(int fd, struct ref *refs, struct extra_have_objects *ext
 	 * parameters by writing to the pipe.
 	 */
 	for (i = 0; i < extra->nr; i++) {
-		memcpy(buf + 1, sha1_to_hex(&extra->array[i][0]), 40);
-		buf[0] = '^';
-		buf[41] = '\n';
-		if (!write_or_whine(po.in, buf, 42, "send-pack: send refs"))
-			break;
+		if (!is_null_sha1(&extra->array[i][0]) &&
+		    has_sha1_file(&extra->array[i][0])) {
+			memcpy(buf + 1, sha1_to_hex(&extra->array[i][0]), 40);
+			buf[0] = '^';
+			buf[41] = '\n';
+			if (!write_or_whine(po.in, buf, 42,
+						"send-pack: send refs"))
+				break;
+		}
 	}
 
 	while (refs) {
-- 
1.6.1.284.g5dc13.dirty