Some changes to the Docker.io code has caused the build script to fail, this was down to the code now using btrfs to build a driver. It has taken me a while to figure out how to fix that error message, but the script now works. You have to add this chunk of code anywhere before the main docker build

git clone git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git
mv btrfs-progs btrfs #Needed to include into Docker code
export PATH=$PATH:$(pwd)
cd btrfs
make || (echo "btrfs compile failed" && exit 1)
export C_INCLUDE_PATH=$C_INCLUDE_PATH:$(pwd) #Might not be needed
export CPLUS_INCLUDE_PATH=$CPLUS_INCLUDE_PATH:$(pwd) #Might not be needed
echo PATH: $PATH
cd ..