Phing-sniff will consider a Use statement unused if it is only being used in a docblock, i.e.:

use Foo\Bar\FooBar

/* @var FooBar */

It should be updated to recognize the statement is in fact used, to prevent test failures.

Example failure: https://travis-ci.org/phpbb/phpbb/jobs/122583594#L940
This is the usage: https://github.com/VSEphpbb/phpbb/blob/ticket/14569/phpBB/phpbb/console/command/user/reclean.php#L36