[bug] clean_url bug

I’m having troubles with clean_url, it’s not properly escaping the ampersands, I tried with a simple echo clean_url( "http://thisisatest.com/error?value=4&value2=5"); but nothing got escaped, I tried to check if some recent change introduced this bug, but could find nothing.

Also I can’t figure out how to submit a bug. Be wary of the fact that this bug is making a clean install of wordpress producing non validating code.