kennethreitz/requests — pull request #755 by enginous (2012-08-03 16:11:44+00:00)
Title: Multipart filenames only sent if provided.

Before this change, `filename` parameter (in `Content-Disposition`) was sent
with every subpart in a multipart even if one was not provided. This changes
request semantics, indicating to the server that the part is indeed a file.

This issue fixes #732.