Travis CI fail seems to be unrelated.

Added a commit but I'm not sure if the added complexity is worth it.

The documentation states:

The MySQL Unix socket (shouldn't be used with host or port).

Still it works fine when port and host are given. So I would argue it's up the the user not specify a host that's not localhost when using the unix_socket param.

I moved around the logic in a way so it became more clear and (hopefully) less complex. Basically: "If you are doing unix_socket, do the complex code. If not, just continue as normally".

@Nyholm Looks like an reasonable improvement for me.

Maybe add the following testcase to be sure the charset option works also when unix_socket is not given:

yield ['mysql://localhost/test?charset=utf8mb4', 'mysql:charset=utf8mb4;dbname=test'];

Great idea.
Yes, please do

Thank you @bcremer.