Integrity problem when cloning git tree onto new btrfs filesystem

I created a shiny new 10G btrfs filesystem on a 2.6.31-rc5 (x86-64 running as Xen domU), and tried cloning a fresh copy of linux-2.6 onto it:

    [jeremy@f11-64 git]$ git clone
    git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    Initialized empty Git repository in /mnt/jeremy/git/linux-2.6/.git/
    remote: Counting objects: 1270263, done.
    remote: Compressing objects: 100% (204288/204288), done.
    Receiving objects: 100% (1270263/1270263), 313.23 MiB | 4485 KiB/s,
    done.
    remote: Total 1270263 (delta 1060042), reused 1268033 (delta 1057934)
    error: inflate: data stream error (incorrect header check)
    fatal: serious inflate inconsistency
    fatal: index-pack failed

Running the same command a second time on the same filesystem completed successfully, as did the same command on an ext3 filesystem. There were no unexpected messages on the console (well, I was a bit surprised it decided to go into SSD mode, but I guess virtual disks are marked as being non-seeking as well).

J