Connect blindly overrides username/password when URI style connection is used.

[ryan-lane]

mongoengine.register_connection(
    'myalias',
    'mydb',
    host='mongodb://localhost:27017',
    username='myuser',
    password=='mypassword'
)

The above will connect to mydb with username None and password None. This is because though a username and password are set, if a uri is used mongoengine will blindly override them: https://github.com/MongoEngine/mongoengine/blob/master/mongoengine/connection.py#L57

Is there any reason not to do 'or username' and 'or password' similar to what's being done for database?

[MRigal]

This is a known bug. The PR #731 almost fixed it, but was never finished. If you feel like helping on the topic, you may complete it, or create a new PR starting from scratch.

[wojcikstefan]

This was fixed by #1428