... at least on my system, that previously could reproduce it.

Will-fix: #5330

... and pave the way for adding more options than the user to execute
the command as.

Will-fix: #9046

Will-fix: #9046

Will-fix: #9046

Will-fix: #9046

Will-fix: #9046

This will fix a similar problem to #8928, which seems to correlate with
CPU load on the host system running the test suite.

"Persistent" in the sense that it survives across scenarios. This is a
first step towards using a single Libvirt::Domain instance across the
full test suite run, which in turn is a step towards being able to use
Libvirt snapshots more easily (or at all, I think).

This was achieved with the following command:

    sed -i 's/@vm\>/$vm/g' -- features/step_definitions/*.rb \
                              features/support/*.rb \
                              features/support/helpers/*.rb

Note that encrypt_sign_helper() already deals with the passphrase by
calling maybe_deal_with_pinentry(), so the removed code may result in
us writing the passphrase a second time, into whatever application has
focus after pinentry closes (Gedit, most likely).

Beyond updating images for GNOME Shell we also remove some bad uses of
wait_*_gnome_window(), since they were previously added in situation
where traditional (2.x) GNOME windows were used, not Header Bars.

Just hovering a sub-menu (e.g. "Accessories") and waiting a bit is enough for
the submenu to open. But we did click on it, and if the sub-menu was already
open by hovering, then clicking closed it, of course resulting in FindFailed
exceptions to be thrown.

First, the pinentry window is not automatically focused in the "Symmetric
encryption and decryption using gpgApplet" feature, for some reason, while it is
focused in the others. So, we click on it to give it focus.

Second, on a fast (bare metal) test setup, when one immediately types the
passphrase, the first character is lost. So, we had a little sleep time. I have
not found any *visible* change during this time, so I can think of no other way
we detect when pinentry is ready to receive our input.

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.

Well, now we have a single variable that changes the live user's name.