I.e. check that

    config/chroot_local-includes/lib/live/config/0001-sane-clock

does what it's supposed to, which is to ensure that the system clock
cannot be set before the Tails build date (if so, we set it to the
Tails build date).

Will-fix: #9377

That means all but those where we rely on the shell, e.g. when we
dot-include a file and chain a command with ; or && like this:

    . path/to/config; echo $var_in_config

In particular in nested VMs it seems 1 second wasn't enough.

Otherwise we definitely cannot trust that the time actually was set.

Now all .feature:s reside directly in the root of features/, and they
are differentiated with tags: source tests are tagged '@source' and
product (i.e. Tails ISO image) tests are tagged '@product'. These tags
then set up the appropriate environment on a feature-by-feature basis.