"git mktree --missing" lazily fetched objects that are missing from
the local object store, which was totally unnecessary for the purpose
of creating the tree object(s) from its input.
source: <748f39a9-65aa-2110-cf92-7ddf81b5f507@roku.com>
* ro/mktree-allow-missing-fix:
mktree: do not check type of remote objects