DevKit updates (#3861)

.travis/install_test.sh

@@ -12,4 +12,8 @@ fi
 wget "https://phar.phpunit.de/${PHPUNIT_PHAR}" --output-document="${HOME}/bin/phpunit"
 chmod u+x "${HOME}/bin/phpunit"
 
+# To be removed when this issue will be resolved: https://github.com/composer/composer/issues/5355
+if [ ${COMPOSER_FLAGS} = '--prefer-lowest' ]; then
+    composer update --prefer-dist --no-interaction --prefer-stable --quiet
+fi
 composer update --prefer-dist --no-interaction --prefer-stable ${COMPOSER_FLAGS}