builtin-pack-objects: don't fail, if delta is not possible

If builtin-pack-objects runs out of memory while finding
the best deltas, it bails out with an error.

If the delta index creation fails (because there is not enough memory),
we can downgrade the error message to a warning and continue with the
next object.

Signed-off-by: Martin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: Junio C Hamano <junkio@cox.net>

builtin-pack-objects.c

@@ -1454,8 +1454,12 @@ static int try_delta(struct unpacked *trg, struct unpacked *src,
 	}
 	if (!src->index) {
 		src->index = create_delta_index(src->data, src_size);
-		if (!src->index)
-			die("out of memory");
+		if (!src->index) {
+			static int warned = 0;
+			if (!warned++)
+				warning("suboptimal pack - out of memory");
+			return 0;
+		}
 	}
 
 	delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);