tmp-objdir: stop using the_repository

Stop using `the_repository` in the "tmp-objdir" subsystem by passing
in the repostiroy when creating a new temporary object directory.

While we could trivially update the caller to pass in the hash algorithm
used by the index itself, we instead pass in `the_hash_algo`. This is
mostly done to stay consistent with the rest of the code in that file,
which isn't prepared to handle arbitrary repositories, either.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -2239,7 +2239,7 @@ static const char *unpack(int err_fd, struct shallow_info *si)
 		strvec_push(&child.args, alt_shallow_file);
 	}
 
-	tmp_objdir = tmp_objdir_create("incoming");
+	tmp_objdir = tmp_objdir_create(the_repository, "incoming");
 	if (!tmp_objdir) {
 		if (err_fd > 0)
 			close(err_fd);