7.04 beta installer problem. No error description when using upercase usernames

Binary package hint: base-installer

Was installing 7.04 beta release. I found that when the installer asked for my user name, if I used uppercase characters in my username I could not move on to next dialogue. BUT I did not get an error telling me I could not use uppercase.

This is a big issue because most people who try and use uppercase in their user name would be newbees and it would be frustrating if they didn't realise what the problem was.