drush gives warning on json parsing in tests

Problem/Motivation

When using drush pmu [module_name] or drush pm:enable [module_name] with whatever module, drush is displaying this warning: [warning] Unable to parse /srv/www/htdocs/[...]/html/modules/contrib/patchinfo/tests/modules/test_composer_syntax_error/composer.json. Check your JSON syntax.

Of course this composer.json has an intended error, because it there for testing, so fixing the corrupt composer.json file is not an option.

Steps to reproduce

Use drush pmu [module_name] or drush pm:enable [module_name]

Proposed resolution

Drush should not check files in tests.

Remaining tasks

Find out why drush is doing that and open an issue at drush.

User interface changes

n/a

API changes

n/a

Data model changes

n/a