Why btrfs module is not included in kernel snapshot builds

Hi,
I found your kernel snapshots build repository at:
http://kernel.ubuntu.com/~kernel-ppa/mainline/

Great job to offer a prebuilt package with the latest kernel snapshot, but why the btrfs module is not included into the build?
The btrfs branch is already in the main repository and it looks like real fun to test it, but I would not like to recompile the kernel every time Linus tags a new version/snapshot (and btw, this is why your repository exists, or I'm missing something?). btrfs-tools package builds already can be found in lp PPAs [1], so please include the btrfs module to you packages. Is it possible?

Thank you in advance.

[1]: https://edge.launchpad.net/~ricotz/+archive/testing