Fix Guzzle following redirects with a custom temporary sink

Fix Guzzle following redirects with a custom temporary sink

When following redirects Guzzle copies over the request options for the next
iteration internally, including the bare `resource` that was passed to it.

This bare resource will then be wrapped into the Stream wrapper. This stream
wrapper explicitely calls `close()` for the underlying resource when it is
being closed.

The created Streams for the subrequests will be closed before the `send`
function returns, thus ultimately closing the resource for the “parent”
request.

Fix this issue by passing a Stream, instead of a bare resource. This one
will be passed along as-is.

Fixes #3529.