Previously, l(o(g(in?)?)?)? meant "login", since only the cmdlen
prefix of the registered command was matched against the sent command.
Discovered by surprisedly seeing "list_room" work.
Apparently weechat sets O_NONBLOCK on a socket:
https://github.com/weechat/weechat/blob/705d86e684d72b8c094e526876db1b8544fd2db3/src/core/wee-network.c#L1105