Are we perhaps mixing the forum "username" with the "name" (used for display only)? This can be seen in Profile / Modify Profile / Account Settings.
No. The attached screenshot shows clearly identical four characters.
When I use UdoB on Trac I get the well known error in the second screenshot. Then I do only edit the capitalization without touching the password - and then it works.
The red box around the edit fields indicates the usage of the Lastpass Add-on which pre-fills the fields. I did test also using Firefox without that one (on Windows 7). In that case I have to enter Username and Password manually.
So I must re-confirm that my observation is unchanged for me, but my workaround.... works.
Best regards