[4.6-rcX regression] closing and opening LID on thinkpad x200s freezes X

Hi,

after updating to 4.6-rcX (where X is 1 or 2, doesn't really matter) on thinkpad x200s notebook with

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

closing and opening the lid freezes the computer completely (after opening the LID, I can see either the complete original contents of the screen, or silouhette of xscreensaver window decorations, but the machine is dead by then (neither ctrl-alt-backspace-backspace nor switching to text console doesn't work).

It definitely worked with older kernels, but I unfortunately don't have all the data needed for bisection, as the old kernels have been wiped off the machine in the meantime.

Is this a known issue?

Thanks,