You can check if a PO file is valid with the following command:

        msgfmt -c -o /dev/null <po file>
      

The following errors were found in ocaml-gettext 's PO files:

gettext: test/testdata/multiline-comment.po: can't guess language
gettext: test/testdata/test1.po: can't guess language
gettext: test/testdata/test11.po: can't guess language
gettext: test/testdata/test12.po: can't guess language
gettext: test/testdata/test2.po: can't guess language
gettext: test/testdata/test3.po: can't guess language
gettext: test/testdata/test4.po: can't guess language
      

Please ask the translator (identified by the Last-Translator field in the PO file), the language team (identified by the Language-Team field) or debian-i18n for a fix.