This basically affects every composer library, MediaWiki extension, and probably more :)
- https://lists.spdx.org/pipermail/spdx-legal/2017-December/002441.html - announcement
- https://www.mediawiki.org/wiki/Topic:U4vb2ru2hcmhwluu - summary of changes related to GPL identifiers
- https://github.com/composer/spdx-licenses/issues/15 - request for composer to support new identifiers
- https://github.com/composer/composer/pull/6969 - integration into composer itself