PHP 7.2.17-1+ubuntu18.04.1+deb.sury.org+3
SYMFONY: Symfony 4.2.4

locale_parse('root') now return an empty array as opposed to previos php versions which makes the Symfony\Component\Intl\Data\Bundle\Reader loop through fallback locales as

"en" => "root" => "" => "root" => "" and so on without it becoming null to break the loop

when reading from the regions because in the Symfony\Component\Intl\Locale::getFallback()
we never get inside the if (1 === \count($localeSubTags))