Reason for objects still being written with a failing pre-receive hook?

["Johan Sørensen" <johan@johansorensen.com>]

Hi,

I'm wondering what the reason is that objects are still being stored,
despite a non-zero exit code from the pre-receive hook?

Obviously refs aren't being updated, but I can see this a gateway for
abuse if I want to control push permissions per ref via the
pre-receive hook (which is the earliest place I know about the ref
being pushed to, unless I've missed something). Basically an abuser
could continuously attempt to push a set of commits with large blobs
to a repo the pre-receive hook doesn't give him access to, and
eventually fill up the repo with useless objects. I could nuke these
with git-prune (after the fact though), but still it seems illogical
that one is allowed to even write the objects in the first place if
the hook fails.

If it's expected and accepted behaviour, what other options do I have
to prevent a scenario like the above?

Cheers,
Johan