http-push: set algorithm when reading object ID

In most places in the codebase, we use oidread to properly read an
object ID into a struct object_id.  However, in the HTTP code, we end up
needing to parse a loose object path with a slash in it, so we can't do
that.  Let's instead explicitly set the algorithm in this function so we
can rely on it in the future.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http-push.c

@@ -1022,6 +1022,8 @@ static void remote_ls(const char *path, int flags,
 /* extract hex from sharded "xx/x{38}" filename */
 static int get_oid_hex_from_objpath(const char *path, struct object_id *oid)
 {
+	oid->algo = hash_algo_by_ptr(the_hash_algo);
+
 	if (strlen(path) != the_hash_algo->hexsz + 1)
 		return -1;