test_xpi often fails at firefox_template.importFromQueue()

I see this 50% of the time I run test_xpi_import:

    Tests with failures:
       testTranslationImport (canonical.launchpad.translationformat.tests.test_xpi_import.XpiTestCase)

I added an assertion after the template is imported from the queue:
        self.firefox_template.importFromQueue()
        transaction.commit()
        self.assertEquals(template_entry.status, RosettaImportStatus.IMPORTED)

The error is always that the status is not IMPORTED
    AssertionError: <Item APPROVED (1) from <class 'canonical.lp.dbschema.RosettaImportStatus'>> != <Item IMPORTED (2) from <class 'canonical.lp.dbschema.RosettaImportStatus'>>