Telnet Password required, but none set on cisco router

If you do not set a tty login password, you'll be locked out of your router... this could be a ajor disaster so make sure you do this before you ship gear!

Router-1#telnet 192.168.1.1

Trying 192.168.1.1 ... Open

Password required, but none set

[Connection to 192.168.1.1 closed by foreign host]
Password required, but none set

Router> en
Router#config t
Router(config)#line vty 0 4
Router(config-line)#login
% Login disabled on line 66, until 'password' is set
% Login disabled on line 67, until 'password' is set
% Login disabled on line 68, until 'password' is set
% Login disabled on line 69, until 'password' is set
% Login disabled on line 70, until 'password' is set
Router(config-line)#password letmein
Router(config-line)#end
Router#write mem