I'm getting the following error when running `composer install` after cloning MW core and checking out 1.25.5. I've gotten the error on two separate systems: 1. Windows with PHP 5.4 and Composer version 1.2-dev 2. CentOS 7 with PHP 5.6 and Composer version 1.1.0 I did NOT get the error on the same Windows machine prior to running `composer self-update`. It had Composer version 1.0-dev (dbdd4978a7dd4cd29d0d7dfc912aab404245b736) prior to update. *** Error message *** Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages. Problem 1 - Installation request for wikimedia/composer-merge-plugin 1.0.0 -> satisfiable by wikimedia/composer-merge-plugin[v1.0.0]. - wikimedia/composer-merge-plugin v1.0.0 requires composer-plugin-api 1.0.0 -> no matching package found. Potential causes: - A typo in the package name - The package is not available in a stable-enough version according to your minimum-stability setting see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details. Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems. *** End error message *** Thanks, James