fallbackLanguage broken after upgrade to 2.9

Subject of the issue

After upgrading from angular 1.4 to 1.5 and angular-translate from 2.8 to 2.9, language switching to “fallbackLanguage” stopped working.

Your environment

• version of angular-translate: 2.9.2
• version of angular: 1.5.0
• which browser and its version: Firefox, Chrome

Steps to reproduce

In our application, language switching stopped working in a strange way. Switching among all languages works, but we cannot switch to ‘en’. After some investigation, we found that dropping

$translateProvider.fallbackLanguage(‘en’);

fixes the switching problems. Here is a part of our code:

.config(function ($translateProvider) {
  $translateProvider.useLocalStorage();
  $translateProvider.useSanitizeValueStrategy('sanitizeParameters');
  $translateProvider.useMessageFormatInterpolation();
  $translateProvider.preferredLanguage('en');
  $translateProvider.fallbackLanguage('en');
  $translateProvider.uniformLanguageTag('bcp47');
  $translateProvider.determinePreferredLanguage();
  $translateProvider.registerAvailableLanguageKeys(['en', 'cs', 'pl'], {
    // en
    'en-AU': 'en', 'en-BZ': 'en', 'en-CA': 'en', 'en-CB': 'en', 'en-GB': 'en', 'en-IE': 'en', 'en-JM': 'en',
    'en-NZ': 'en', 'en-PH': 'en', 'en-TT': 'en', 'en-US': 'en', 'en-ZA': 'en', 'en-ZW': 'en',
    // cs
    'cs-CZ': 'cs',
    //pl
    'pl-PL': 'pl'
  });

  $translateProvider.useLoader('$translatePartialLoader', {
    urlTemplate: 'modules/{part}/{lang}.json',
    loadFailureHandler: 'SITranslationErrorHandler'
  });
  $translateProvider.useLoaderCache(true);
})

.run(function ($rootScope, $stateParams, $translate, $translatePartialLoader){
  $rootScope.$on('$stateChangeSuccess', function () {
    if ($stateParams.lang !== undefined){
      $rootScope.activeLang = $stateParams.lang;
      $translate.use($stateParams.lang);
      $translatePartialLoader.addPart('translation');
      $translate.refresh();
    }
  });
});

Another way how to fix switching (but without dropping fallback language) is to move fallback language to .run() block:

$translate.fallbackLanguage(‘en’);

and change useLocalStorage to useCookieStorage. Just one of these changes was not sufficient.

Expected behaviour

Language switching should be working - language should be switched.

Actual behaviour

Language switching is working except that switch to “fallbackLanguage” is ignored.

[knalli]

Published 2.10.0 few minutes ago, including the PR by @tspaeth .

[sebek64]

Confirming that 2.10.0 fixes the bug, thanks to all who worked on the solution.