Getting the error text from `urllib2.urlopen`

I us开发者_StackOverflow中文版ed Python's urllib2.urlopen and got a 500 error from the server. How do I find the text of the error? I'm hoping that it has useful information.

from urllib2 import urlopen, HTTPError

try:
    f = urlopen(url)
except HTTPError, e:
    print(e.read())