This was previously 7.0 which lacked support for the M2SETUP_USE_COMPOSER_ENTERPRISE variable, and also didn't match the image version in use for phpfpm.
@@ -37,7 +37,7 @@ dbdata:
- /var/lib/mysql
setup:
- image: mageinferno/magento2-php:7.0-fpm-0
+ image: mageinferno/magento2-php:7.1-fpm-0
command: /usr/local/bin/mage-setup
links:
- db