[3.9] bpo-19460: Add test for MIMENonMultipart (GH-29817)#29819

asvetlov merged 2 commits into

python:3.9python/cpython:3.9from

miss-islington:backport-46c8d91-3.9miss-islington/cpython:backport-46c8d91-3.9Copy head branch name to clipboard