This applies to the kernel: 4.2.2-5.g87b68a3-default 64 bit and a 13.2
otherwise unmodified system. 
Running stable kernels for nearly a year now. The last aforementioned update
introduced the following problem:

Put a X201 on its docking station, lid closed. The keyboard is USB external
attached to one of the USB ports (no matter if the docking or the notebook
ports).
When you light up, the password of Bios and HDD are taken without discussion. 
Then you can you can choose normally the OS. As soon as the OS takes over, the
external USB keyboard switch off, does not react and also appears not to have
even current any more. This while monitor works flawlessly. Other devices seem
to work normally. 
Spy led on num-lock or caps e.g. do not work any more. 
If you open the lid, you can input the LUKS password for the machine without
problem. 
Now if you attach the keyboard to usb it will work once the OS has started. As
you close the lid, the PC will go to sleep, to wake up now you CAN
astonishingly use the external keyboard (pressing enter or the respective FN
key. Now you can work with the lid closed normally. Up to the next reboot where
this starts over from the scratch. 
Reproducible allways. Hardware X201 with the respective dockingstation
ultrabase (the one also called sometimes "Oilsump", just to understand the
model).