*lock* considered empty?

[James Dennis]

Is *lock* considered empty in regard to passwords? I have an account 
that was locked using *lock* as the password (not my system) and after 
upgrading to 3.7.1 we found that that account could not log in. After 
giving that account a password, it could login fine. We were using 
public key auth so passwords aren't even necessary for that account.

-James