Ok, here comes yet another version of the patch, addressing the review comments.

As indicated in the last post and requested by Martin, I moved the logic to deal with the different body types out of send() into _send_output().  I also removed the conversion from byte-like to bytes.

I had some problems with some comments mainly on the documentation of urllib.request, asking for stuff unrelated to chunked transfer encoding and the present issue.  I have the impression this is starting to get out of hands.  Time is running out and I suggest that we should keep the focus on the present issue.

There were also requests to drop support for stuff that is working in the current library, although not documented, and that is explicitly covered by the test suite.  I'm fine with dropping that and also adapted the tests accordingly.  But please be sure that what you are asking for is really what you want.

Please note that this patch is not yet complete.  I still need your decision on the two issues raised in the last post: the test method to use for text streams and whether I should drop the sanity checks for the transfer-encoding header.