Comment 4 for bug 1671991

Debian stretch has the opposite issue: there, rescue only works if no desktop session is active. Otherwise, whether systemctl is run from within that session or not, the console is left completely unusable; not even Ctrl+Alt+Del works.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=858162 exists for that, but the Xenial issue is completely different: the console never becomes unresponsive. Instead, the system is stuck in some intermediate state where the normal getty is stlil alive, but login is not allowed, and the actual rescue prompt is never reached.