Slow pushes on 'pu' - even when up-to-date..

This seems to be because I'm now on 'pu' as of a day or two ago in order to test the abbrev logic, but lookie here:

    time git ls-remote ra.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux
    .. shows all the branches and tags ..
    real 0m0.655s
    user 0m0.011s
    sys 0m0.004s

so the remote is fast to connect to, and with network connection overhead and everything, it's just over half a second. But then:

    time git push ra.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux

and it just sits there, and it's at 100% CPU the whole time, until it says:

    Everything up-to-date

    real 1m7.307s
    user 1m2.761s
    sys 0m0.475s

Whaa? It took a *minute* of CPU time to decide that everything was up-to-date?

That's just not right. The branch is entirely up-to-date:

    git rev-parse HEAD
    af79ad2b1f337a00aa150b993635b10bc68dc842

    git ls-remote ra.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux master
    af79ad2b1f337a00aa150b993635b10bc68dc842 refs/heads/master

so there should be no need for any history walking. But it sure is doing *something*. A minute of CPU time on my machine is actually a pretty damn big deal.

Looking at the trace, there's no IO - there's no back-and-forth about "I have this, do you have it?" or anything like that. The system call trace is just a lot of allocations, which I think means that "git push" is walking a lot of objects but not doing anything useful.

I bisected it to commit 60cd66f "push: change submodule default to check", which makes little sense since I have no submodules, but there you go.. Apparently RECURSE_SUBMODULES_CHECK is just terminally broken.

                Linus