No waiting for 266 or 250 transfer anymore

Some clients do not close the data connection until they receive the 226 response from the server.
This behavior is permitted by RFC 959. (The intent, now obsolete, was for clients to retrieve multiple
files through one data connection, with a self-delimiting encoding of each file. The server could use
226 to say that it was closing the connection, or 250 to say that it wasn't. The most obvious client
implementation wouldn't close the connection until it received 226.) However, I recommend that clients
close the data connection immediately after seeing the end of data. One server, wu-ftpd 2.6.0, waits
until the client closes the connection before it sends its 226 response; this screws up file transfers
to clients that do not close the data connection immediately. This also wastes a round-trip time for other
clients. (As of 1999, various versions of wu-ftpd run about half of the Internet's FTP servers. Many
servers made an emergency switch to version 2.6.0 in October 1999 when major security holes were
discovered in previous versions.)

Referred from https://cr.yp.to/ftp/retr.html

Fix #14 and original resolver mscdex#259

Thanks @std4lqi