Comment 2 for bug 966251

The 64 character limit (on using SQL backend) is an issue because without that, it will raise a Conflict on registering an user whose first 64 characters match to an existing user. Which could have been avoided in the first case while registering the first user with long name.
Also, another issue is user is not aware/notified about the name being truncated, so he has no idea of how the name conflicts with the existing user (since new user's name differs say after the 64th character).