Python может механизировать, обрабатывают автора HTTP?

Mechanize claims that the parameters should be uri, username and password as parameters, but you have four parameters. Four parameters are correct for urllib2.add_password, but then the first parameter should be the realm, not the uri.

http://wwwsearch.sourceforge.net/mechanize/

I'd try to change that first.

Does trac require digest? if not a next step could be to try using basic auth, as a test to see if that works, since you can add that with just addHeader:

import base64
from mechanize import Browser
browser = Browser()
browser.addheaders.append(('Authorization', 'Basic %s' % base64.encodestring('%s:%s' % (user, pwd))))

#!/usr/bin/env python
# -*- coding: utf-8 -*- 

import mechanize

a=mechanize.Browser()
a.open("http://www.facebook.com/login.php")
a.select_form(nr=0)  #form number.
a["email"]="mailaddress"
a["pass"]="password"
a.submit()
print a