Allan Caffee [off-list ref] writes:
Is there a way to explicitly fetch whatever objects are necessary to checkout
the commit?
One security principle built into git is that any object that is
unreachable from refs/* is not to be exposed to outside world. If the
commit is not on any ref, you shouldn't be able to obtain it remotely.
So you need to know which branch (or it could be a tag) the commit you
want is on, fetch that branch or tag and then check the commit out.