I've noticed that when reading from mo files the msgctxt is not correctly handled, and it is treated as part as the msgid of an entry.
See the attached test for details. In that particular case, I'm reading from an mo file and when printing the msgid of entries that have a msgctxt, the msgid contains the msgctxt and the msgctxt is empty. E.g. (printing an msgid)
msgctxt "Stock label" msgid "_Open" msgstr "_Obre"
print entry.msgid Stock label_Open }}}