streaming: convert open_istream to use struct object_id

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/archive-zip.c b/archive-zip.c
index 5841a6c..18b951b 100644
--- a/archive-zip.c
+++ b/archive-zip.c
@@ -337,7 +337,7 @@ static int write_zip_entry(struct archiver_args *args,
 
 		if (S_ISREG(mode) && type == OBJ_BLOB && !args->convert &&
 		    size > big_file_threshold) {
-			stream = open_istream(oid->hash, &type, &size, NULL);
+			stream = open_istream(oid, &type, &size, NULL);
 			if (!stream)
 				return error("cannot stream blob %s",
 					     oid_to_hex(oid));