Fix the prefer-lowest job on Travis

Author: stof

.travis.yml

@@ -29,6 +29,8 @@ cache:
     - $HOME/.composer/cache
 
 before_install:
+  # To be removed when this issue will be resolved: https://github.com/composer/composer/issues/5355
+  - if [[ "$COMPOSER_FLAGS" == *"--prefer-lowest"* ]]; then composer update --prefer-dist --no-interaction --prefer-stable --quiet; fi
   - if [ "$DEPENDENCIES" != "" ]; then composer require --no-update $DEPENDENCIES; fi;
   - echo "memory_limit=2G" >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini