Now the test shows the behavior when is requested a translation to an undefined locale catalogue and, therefore, the fallbacklocale catalogue must be queried. The original test function only checks the step to reach the language catalog not to the fallbacklocale one (even the fallbacklocale isn't set). This test gives error in the current version of symfony/symfony.
This allows the translations to be deeply nested arrays that will be flattened, allowing for namespacing of translations easily.
The following:
'key' => array('key2' => array('key3' => 'value'))
Becomes:
'key.key2.key3' => 'value'
This isn't applied to Xliff since it does not make sense within the scope of the XLIFF standard