Add missing assert for test "correctly redirects for a file whose fiename contains something looking like a hash"

The path provided in the test "/robots-3e.txt" is dehashified to "/robots.txt", which is then hashified to "/robots-ca121b5d03245bf82db00d14cee04e22.txt". This is not  match for the expected url. The added assert now shows a failure.

Either we should change the expected value in the test to "/robots-ca121b5d03245bf82db00d14cee04e22.txt"
_OR_
We should ONLY dehashify urls that contain actual 32 character hashes

I am not certain why we would want to redirect for filenames that have something that looks like a hash, rather than actually having a hash.