Without this, the second time it tries to stop in a parametrized
function it raises instead:
`ValueError: --trace can't be used with a fixture named func!`
Implementation idea, test (and changelog tweaks) thanks to blueyed
Co-Authored-By: Ronny Pfannschmidt <opensource@ronnypfannschmidt.de>
Co-Authored-By: Daniel Hahler <git@thequod.de>
David Szotten