MariaDB no database password - Incorrect syntax or a bug?

[distinctjuggle]

let database_url = "mysql://username@localhost/database?user=username";
let database_url = "mysql://username:@localhost/database?user=username";
let database_url = "mysql://username:@localhost/database?password=";
let database_url = "mysql://username:''@localhost/database?password=";
let database_url = "mysql://'username':@localhost/database?password=";
let database_url = "mysql://username:@localhost/database";

I've tried the above, along with several others, and I'm not getting anywhere with them. Either the username will not be recognized by the syntax (with an error similar to: "Access denied for user ''@'localhost' to database xxx - note the empty single quotes around the username) or the password will be interpreted as something other than a blank/empty password, and will thus be incorrect. Am I doing something wrong, or is this old issue back? #203

If I'm doing something wrong, what would the correct syntax be?