2
<MultipartPart [5 bytes]> [('content-type', 'text/plain'), ('x-custom', '1'), ('x-custom', '2')] b'hello'
<MultipartPart [18 bytes]> [] b'empty-headers part'
repeatable OK
zero parts OK
not-multipart raises: Cannot decode multipart content from 'text/plain' responses.
streaming: [b'split'] closed: True
second iteration raises StreamConsumed
