Comment 49 for bug 516412

Regarding the workaround mentioined in comment 1, after downgrading the package you may want to prevent automatic upgrades pf plymouth and libplymouth2
To do this, open a root terminal and give the following commands:
# dpkg --set-selections
plymouth hold
libplymouth2 hold

and exit with Ctrl+D (NOT Ctrl+C)

To revert back when this will be fixed:

# dpkg --set-selections
plymouth install
libplymouth2 install

and exit again with Ctrl+D

To check the package status
# dpkg --get-selections plymouth
# dpkg --get-selections libplymouth2