This package is mostly needed as a build dependency for the next version of SpeedCrunch (
https://tracker.debian.org/pkg/speedcrunch). Regarding the quilt patch: tinycss is an optional dependency that is only necessary to run certain tests; if it's not available, the tests in question are skipped. However, as long as it's in tests_require, pybuild tries and fails to install when running the tests so I removed it from tests_require for the package.
Regards,
Felix