The design of po4a seems to expect it to act as a build system,
running with a config file telling it which files to build. In
version 0.68-1, the po4a-gettextize tool has changed to error out
with a comment that it's not being run the way it expects.
See https://bugs.debian.org/1020821
po4a-updatepo works for now with 0.68-1, although it prints a deprecation
message.