Description of problem:

When trying to fetch files using a proxy for https connections,
urlgrabber gives a traceback. I guess the problems is in the
urllib/urllib2 module so filing against python.

Version-Release number of selected component (if applicable):
python-2.4.3-43.el5.x86_64
python-urlgrabber-3.1.0-6.el5.noarch
squid-2.6.STABLE21-6.el5.x86_64

Steps to Reproduce:
1. yum install -y mod_ssl squid
2. mkdir /var/www/html/grabber && touch /var/www/html/grabber/file.html
3. service httpd start
4. sed -i 's/allow localhost/allow all/' /etc/squid/squid.conf
5. service squid start
6. export https_proxy=http://`hostname`:3128
7. urlgrabber https://`hostname`/grabber/file.html file.html
  
Actual results:
Traceback (most recent call last):
  File "/usr/bin/urlgrabber", line 124, in ?
    main()
  File "/usr/bin/urlgrabber", line 120, in main
    filename = urlgrab(url,filename=file,**kwargs)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 602, in urlgrab
    return default_grabber.urlgrab(url, filename, **kwargs)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 936, in urlgrab
    return self._retry(opts, retryfunc, url, filename)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 854, in _retry
    r = apply(func, (opts,) + args, {})
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 922, in retryfunc
    fo = URLGrabberFileObject(url, filename, opts)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1010, in __init__
    self._do_open()
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1093, in _do_open
    fo, hdr = self._make_request(req, opener)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1216, in _make_request
    raise new_e
urlgrabber.grabber.URLGrabError: [Errno 14] HTTP Error 503: Service Unavailable

Expected results:
file written to file.html

Additional info:
Seems that urllib expects "https" in the proxy specification, but
I believe this is wrong. Unfortunately I was not able to find any
specification about how the https_proxy URL should look like. But
it seems "http" is commonly used. So the following can be used as
a workaround:

    export https_proxy=https://`hostname`:3128

Works fine with wget.