Merge branch 'jc/maint-undefined-i18n-observation-test'

It was unclear what a test in t0204 wanted to check; it turns out
that it was only to observe an undefined behaviour of the system,
and did not anticipate one kind of reasonable error behaviour.

* jc/maint-undefined-i18n-observation-test:
  t0204: clarify the "observe undefined behaviour" test