It looks like module-cgi cannot handle GET and POST together when using
FieldStorage. For instance, a <form action="script.py?key=value"
action="post"> is available through cgi.FormContent but not
cgi.FieldStorage when there are other <input> in the html form.
Very strange.

Well, what are you waiting for? Submit a patch!

Here it is, babe. I've made appropriate changes to make it read
QUERY_STRING when it's available within POST method. It's currently
being parsed by parse_qsl() in read_urlencoded() as it should be in
regular GET or POST. I didn't touch CONTENT_LENGTH since it has the size
of the POST data without QUERY_STRING's size. That would affect read()
of such POST data. It's working. Thanks for the incentive, it's my first
patch for python.

Now I added support for parsing query string within multipart/*. The
only issue now is that it mixes FieldStorage with MiniFieldStorage.
However, I don't think it's a problem.

Here's the unit test for patched cgi module.
There are three tests: one for HTML POST forms that are urlencoded, and
two for multipart/form-data - with and without file upload.

This was pretty much done when I got here. It broked the other cgi_test
(which tests some other corner cases).
Patch includes modifications to Lib/cgi.py and adds
Lib/test/test_cgi_post_qs.py to test the new features.
This should be closed by now, but since this is my first patch, just let
me know what else should I do to get it closed.
thanks!

Thanks for your contribution!
To get this commmitted, please draw the attention of someone else on
python-dev (or if you're an IRC person try #python-dev at freenote,
IIRC).  I'd recommend moving the tests into the existing test_cgi.py.

I moved the test into the current test_cgi.py, and also added the docs
and NEWS.
This patch also includes all the previous changes and is the only one
that needs to be merged.
Now I think it def should be closed :)

Commited the final Nubis' version in r64447. Fixed, :). Thank you all!