Comment 90 for bug 1637601

I picked up a report today on IRC which I wanted to discuss here with the audience that created the change.

The report was that with 16.04.2 the libvirt user now shows up on e.g. gdm dropdown when selecting users.

I thought it filters system users, but then --system (=get a low number) and providing the number from base-passwd kind of oppose each other.
Yet I seem not to have puzzled together the full picture, there are many more UIDs in base-passwd yet I never heard about those in gdb.
Would there be a different option that one has to set to "create" them differently?