boto/boto — pull request #702 by sievlev (2012-04-13 11:17:36+00:00)
Title: urllib.quote_plus brake headers

urllib.quote_plus brake headers,
e.g., header { "content-type": u"image/png" } will became { "content-type": "image%2Fpng" }

You shouldn't perform urlencode at this level of library.