Composer installs path repositories as symlinks by default, which causes Magento's template engine to fail when resolving .phtml files. Setting `COMPOSER_MIRROR_PATH_REPOS=1` on all composer install steps forces a copy instead, matching how the package would be installed from Packagist in production.
Adds a .phtml template and an integration test to the demo package that
renders it via Magento's template engine. Without COMPOSER_MIRROR_PATH_REPOS=1
the path repo is installed as a symlink and the test fails; with mirroring
it passes.
Closes#217
BREAKING CHANGE: Much of the "setup" that's built-into the command is removed in favor of a leaner action. This also includes the "on PR, only diff PR contents" behavior. This can be restored, but it shouldn't be the default and should be done as an input.
Fix SEVERITY_FLAGS construction which exited 1 under bash -e when
severity inputs were empty, causing CI failures.
Damien Retzinger
David Lambauer