Some suggested package, such as doctrine-fixtures-bundle requires a specific version to work (for fixtures it's 3.0), but because they are only suggested dependencies, no check are done on the version.
So someone that have the doctrine-fixtures-bundle in 2.0 will see a message doctrine/doctrine-fixtures-bundle must be installed to use this method. (per #437) but nothing related to the version.
Not sure how it can be handled in a clean way.