Here is my analysis:

>>> import urllib2
>>> url = "http://www.mercurynews.com/ci_9216417"
>>> content = urllib2.urlopen(url).read()
>>> print content

>>> opened = urllib2.urlopen(url)
>>> print opened.geturl()
https://secure.passport.mnginteractive.com/mngi/servletDispatch/ErightsPassportServlet.dyn?url=http://www.mercurynews.com/ci_9216417?nclick_check=1&forced=true

# This URL Redirection is a 302 Redirection. 
# Browser is "unable" to launch the redirected site.
https://secure.passport.mnginteractive.com/mngi/servletDispatch/ErightsPassportServlet.dyn?url=http://www.mercurynews.com/ci_9216417?nclick_check=1&forced=true
# Logically, the urllib /urllib2 is giving a Blank when reading this site.

I would't entire say urllib2's fault before understanding how FF is
handling the redirection of the first site.
1) Open the site mentioned in the Location of 302, you will experience
the same behaviour as 302.

It seems more of an issue at server end, we have to know how, Firefox is
handling at the first place.