Steps to reproduce the problem:
1. register a custom protocol (let's say "customProtocol") to launch an app using %U as described at https://developer.gnome.org/integration-guide/stable/desktop-files.html.en#tb-exec-params
2. run "xdg-open customScheme://a/b/?url=https://www.jhack.it/blog/"
What is the expected behavior?
The app receives exactly the string "customScheme://a/b/?url=https://www.jhack.it/blog/".
What went wrong?
The app receives "customScheme://a/b?url=https://www.jhack.it/blog/".
The slash after "b" is removed.