So i diffed the system directories of CM 10.1 and Ubuntu Touch and found the new files.
I pushed those files to my working CM 10.1 installation on the GNex.
Since I did not wipe my GNex when I went back from Ubuntu Touch to CM 10.1, the folder structure
of Ubuntu stayed at /data/ubuntu/.
Then, I rebooted into the bootloader and flashed the boot.img of Ubuntu Touch to the GNex.
After rebooting, the device was stuck at the Google boot logo but the kernel did actually boot, so I was able to adb shell into the device.
<6>[ 15.739807] PVR_K:(Error): BridgedDispatchKM: Initialisation failed. Driver unusable. [4783, /home/ubuntu/jenkins/workspace/phablet-image/kernel/samsung/tuna/drivers/gpu/pvr/bridged_pvr_bridge.c]
That means Canonical still uses the kernel from before a week, this kernel doesn't play nicely with the new proprietary GPU driver.
I'll try pushing the old GPU blobs now...