While the original code did do some checking on usernames to make sure they didn't have leading spaces, it would completely ignore the spaces if prepended with a color code, letting the user have a blank name, or atleast a name with 3 spaces before the rest of the text. 

This would allow players to "clone" other players names, enabling them to hide while cheating. I've briefly tested this patch and assume it will work correctly, though I haven't checked it against any mods.

This patch affects game code only, it will be up to mod developers to incorporate it into their games. Though it is an easy fix.