Debug output doesn't show a difference for foo: and foo://

[glandium]

use url::Url;
fn main() {
  assert_eq!(Url::parse("foo:"), Url::parse("foo://"));
}

shows:

thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `Ok(Url { scheme: "foo", username: "", password: None, host: None, port: None, path: "", query: None, fragment: None })`,
 right: `Ok(Url { scheme: "foo", username: "", password: None, host: None, port: None, path: "", query: None, fragment: None })`', src/main.rs:3:3

(playground link)

There is no visible difference between left and right. Now, imagine the real code being assert_eq!(my_func(), Url::parse(expected).unwrap()); and seeing this error.

[glandium]

Needless to say, the re-serialization with .as_str() does differ between the two values.

[djc]

Yeah, I think I ran into similar problems before. What do you think we should put into the Debug impl instead?

[glandium]

Maybe exposing cannot_be_a_base would be enough?

[djc]

See #699.