This is the itstool part of https://bugzilla.gnome.org/show_bug.cgi?id=660231

If a translation has some wrong tag (like "</gui>test<gui>"), then itstool 1.1.1 crashes:

  File "/usr/bin/itstool", line 974, in <module>
    doc.merge_translations(translations, opts.lang)
  File "/usr/bin/itstool", line 657, in merge_translations
    self._check_errors()
  File "/usr/bin/itstool", line 336, in _check_errors
    raise libxml2.parserError(self._xml_err)
libxml2.parserError:  Entity: line 1:  parser  error :  Opening and ending tag mismatch: title line 1 and gui

The right thing to do here is to not just ignore the translation (and fail during make check).