When the current locale catalogue doesn't contain the id searched, the code doesn't search in the fallbacklocale catalogue (as is explained in the documentation).
Added the search to the fallbacklocale catalogue to the translation function.

…he current locale catalogue.

When loading a catalogue the function "optimizeCatalogue" add the fallback catalogue to the current locale catalogue. This should be done by first adding the language catalogue and finally adding the fallbacklocale catalogue specified in the configuration. This subsequent additions are done by the "loadCatalogue" function.

The problem is that in the "loadCatalogue" function exists an if statement that checks if the resource of a given locale exists before loading it. If not, the function simply returns. This return implies that the subsequent addition of the fallbacklocale wouldn't be done.

This has been fixed by simply replacing the current if statement and adding a new one that, if the resource exists, then executes the process of resource loading. Finally, the function continue calling the "optimizeCatalogue" function.

…cale"

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.