This is a very good move for security on all of our Drupal 8 sites.
"As a best practice, development tools should not be deployed on production sites. Accordingly, packaged Drupal 8 stable releases will no longer contain development PHP libraries, because development code is not guaranteed to be secure or stable for production."
url:
https://www.drupal.org/blog/drupal-8-will-no-longer-include-dev-dependencies-in-release-packages
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