We used to return subsystem names (without the "core_" prefix) and moodlecheck was prepared to handle that when validating @package tags.

Some weeks ago we decided to move to proper component names (including the core_), so moodlecheck surely needs some minor fixing to get the new names being properly verified.

Example of false-positive: core_backup @ http://integration.moodle.org/job/Precheck%20remote%20branch/167/