lib/implementation.js
function inferMaster() {
      var inferred = _.find(self.nestedLocales, { name: self.defaultLocale }) || self.nestedLocales[0];
      if ((self.nestedLocales.length > 1) && (!_.find(self.nestedLocales, function(locale) {
        return locale.children && locale.children.length;
      }))) {
        var others = _.filter(self.nestedLocales, function(locale) {
          return locale.name !== inferred.name;
        });
        self.nestedLocales = [ inferred ];
        if (others.length) {
          inferred.children = others;
        }
      }
    }
function inferMaster() {
      var inferred = _.find(self.nestedLocales, { name: self.defaultLocale }) || self.nestedLocales[0];
      if ((self.nestedLocales.length > 1) && (!_.find(self.nestedLocales, function(locale) {
        return locale.children && locale.children.length;
      }))) {
        var others = _.filter(self.nestedLocales, function(locale) {
          return locale.name !== inferred.name;
        });
        self.nestedLocales = [ inferred ];
        if (others.length) {
          inferred.children = others;
        }
      }
    }
If there is no locale hierarchy, infer that the default locale is the master, or the first locale if there is no default. This is a bc gesture, master locales are a best practice