DecodingFilter and URIs
DecodingFilter should also decode the request path and the parameter names, not only the parameter values. See:
According to the spec, it should always use UTF-8, though allowing the user to override this is probably acceptable.
This fix makes even more sense when using positional parameters:
def default(self, word): return word
With the above code, there is no reason why /?word=perché should work and /perché shouldn't.
Reported by steadicat