extract_cookies_to_jar requires a response with _original_response

[dstufft]

While attempting to make a LocalFSAdapter() which handles file:// urls I discovered that the response objects need to have an _original_response attribute or it bombs out at https://github.com/kennethreitz/requests/blob/master/requests/cookies.py#L113.

[sigmavirus24]

This probably doesn't help but a few things:

• Requests is ill-suited for the file:// scheme.
• The _original_response object can be faked in a couple ways but only one way if you're interested in python 2 and 3 support. If the latter is your purpose then checkout sigmavirus24/betamax. I'm using the latter method there. If you have questions, feel free to ask me outside of this message.

I also wouldn't be opposed to documenting the method, but for the most part, I don't see this being a bug. Maybe @Lukasa or @kennethreitz

[dstufft]

Heh, @kennethreitz is the one who told me to file it :) I actually have it mocked and it's pretty janky. Simple fix for upstream though and the file:// url is actually working pretty well, requests seems to handle it fine. The only "gotchas" are this one which requires a pretty janky hack to get around, and an error because file:// urls don't have a hostname but another small hack can fix that too.

FWIW: dstufft/pip@aba6f37

[sigmavirus24]

The fix is simple without a doubt and since it seems @kennethreitz seems okay with it, I'll put together a PR with it.

That said, the best workaround is not that janky frankly but you're right in that it shouldn't be necessary. My project needs it though :/