Composer version mismatch

[Flower7C3]

This statement

docker-ci-php-node/3.0/Dockerfile

Line 60 in 49e8642

composer self-update

installs composer in version 2. But some projects still need version 1. If someone need to back to version 1 please add --1 this line or follow official instructions about programmatically installation https://getcomposer.org/doc/faqs/how-to-install-composer-programmatically.md
Maybe You can add some variable for this problem?