kennethreitz/requests — pull request #1012 by bodziec (2012-12-16 15:01:40+00:00)
Title: Fixed small bug where user couldn't add custom headers

I think someone made a typo:

self.headers = CaseInsensitiveDict(self.headers)

should be:

self.headers = CaseInsensitiveDict(headers)

Cheers,
Bartek