Downgrade po4a to Stretch's 0.47-2
It seems we won’t manage to do #17005 by upgrading All The Things to po4a 0.55 in time for Tails 4.0, so for now let’s do it by ensuring all relevant systems run 0.47-2.
Feature Branch: bugfix/17127-po4a-from-stretch
Related issues
Original created by @intrigeri on 17127 (Redmine)