upload_file method did not consider the provided file name

The call client.upload_file('hello.txt', open('/path/to/file/test.txt‘,'rb')) resulted in the file test.txt on box.com.

The multipart message in the post request looked like the following:

--22f4070af4404a26b26e8af463325ac1
Content-Disposition: form-data; name="hello.txt"; filename="test.txt"
....
--22f4070af4404a26b26e8af463325ac1--

This could be fixed by changing the files parameter on requests.post to "files={filename: (filename, fileobj)}".