Bug#878851: Info received (Bug#878851: Acknowledgement (libgl1-mesa-dri: after updating the mesa libs from 13.0.6 to 17.2.2 X does not start any longer))
from /var/log/Xorg.0.log.old: [ 7.182] (EE) Failed to load /usr/lib/xorg/modules/extensions/libglx.so: /usr/lib/x86_64-linux-gnu/libGL.so.1: undefined symbol: _glapi_tls_Current
Bug#878851: Acknowledgement (libgl1-mesa-dri: after updating the mesa libs from 13.0.6 to 17.2.2 X does not start any longer)
PS: only chance to to get the machine working was booting in rescue mode and reinstalling 13.0.6