We use PHPUnit's @ticket annotation to refer to GitHub issues,
but still want to use WP_UnitTestCase for its various factory
methods, so we subclass it and stub out the Trac-checking part. :)
Empty method to disable integration with WP Core Trac.
Overrides the parent's method to disable fetching information
from the WordPress Core Trac ticket tracker which causes tests
with the @ticket annotation in our own test cases to fail.