Improve debugging message of invalid URLs
Improve debugging message of invalid URLs

(cherry picked from commit f85e6bf2b9b099593a6a1ba32590cda9b058e38b)

ghalse/simplesamlphp,simplesamlphp/simplesamlphp,simplesamlphp/simplesamlphp,ghalse/simplesamlphp,simplesamlphp/simplesamlphp,ghalse/simplesamlphp,ghalse/simplesamlphp,simplesamlphp/simplesamlphp