2.0.0-RC2 - released 2020-10-14

Changelog

Breaking: Removed OperationInterface::getReason as the data was not accurate
Added automatic removal of packages which are not required anymore whenever an update is done, this will purge packages previously left over by partial updates and require/remove
Added shorthand aliases -w for --with-dependencies and -W for --with-all-dependencies on update/require/remove commands
Added COMPOSER_DEBUG_EVENTS=1 env var support for plugin authors to figure out which events are triggered when
Added setCustomCacheKey to PreFileDownloadEvent and fixed a cache bug for integrations changing the processed url of package archives
Added Composer\Util\SyncHelper for plugin authors to deal with async Promises more easily
Added $composer->getLoop()->getHttpDownloader() to get access to the main HttpDownloader instance in plugins
Added a non-zero exit code (2) and warning to remove command when a package to be removed could not be removed
Added --apcu-autoloader-prefix (or --apcu-prefix for dump-autoload command) flag to let people use apcu autoloading in a deterministic output way if that is needed
Fixed version guesser to look at remote branches as well as local ones
Lots of minor bug fixes and improvements