What steps will reproduce the problem?

1. Use LDAP backend.
2. Log in to have reviewboard create the user in the User table.
3. Log out.
4. Log in again with some spaces in front of your username.  It should
successfully log in, and it will create a new row in the User table with
the spaces.  Subsequently, doing things like clicking on the "Submitters"
link on the dashboard will fail because it finds usernames with spaces in them.

This happens with either the website or post-review.  I saw a few users
with spaces, tabs, or newlines in front of their username (not sure how
these clever users managed to get a newline in there).

What is the expected output? What do you see instead?

It should either reject the login or strip the whitespace automatically.

Please provide any additional information below.

I'm not sure if it matters what the LDAP server is or what the exact UID
mask is.  If you can't reproduce it, I can provide more detail.