Here is a couple of patches to minimize debian and ubuntu difference. In
both distros, we can configure multiple themes. Debian hardcodes the
"text" one as a text alternative and duplicate some logic to copy the
module and such.
The first patch aims at removing that duplication and introduce a more
flexible way to configure a "text" based theme (and not harcode modules
which can be fetched from the .plymouth file)

The second patch is only for the sake of minimizing debian-ubuntu diff,
as we don't ship the plymouth defaults file but use 2 alternatives. This
one is less useful to debian.

Tell me if anything needs to be modified or if you have any question!
Cheers,
Didier