Check out http://stackoverflow.com/questions/9327597/python-get-does-not-evaluate-to-true-even-though-there-is-an-object 

It turns out a cgi.FieldStorage object may consider itself False even when it has data.  This happens when the initialization decided to use read_single() instead of one of the other ways of reading the field value (read_urlencoded() or read_multi()).  Then self.list remains None, and __nonzero__ returns False no matter what the contents of self.file is.

To make things worse -- or better? -- the Python 3 version still defines __nonzero__() instead of __bool__().