System is not locked when resuming from hibernate

[Christoph Grimmer-Dietrich]

I found the following issue:

I'm running Ubuntu 15.04 on a Dell Latitude E6530 with a more or less default install. I activated Suspend to Disk because at times I have the laptop lying around unused for the weekend without plugging it a power outlet.

When calling

sudo systemctl hibernate

from a console the system goes to sleep as intended but simply resumes operation directly on the desktop when waking up even after several days. This makes the hibernate pretty unusable out of the confines of my home.