Use --protocol=tcp as socket connection is available earlier.

Author: arvenil

.travis.yml

@@ -70,7 +70,7 @@ before_script:
   # run docker containers
   - docker-compose up -d
   # wait for MySQL to become available
-  - ./with_backoff.sh docker-compose exec mysql mysql -u"${MYSQL_USER}" -e 'SELECT 1'
+  - ./with_backoff.sh docker-compose exec mysql mysql --protocol=tcp -u"${MYSQL_USER}" -e 'SELECT 1'
   # log versions
   - docker --version
   - docker-compose --version