This does almost(*) only pure merge. We will slaposify / adjust config
and corresponding md5sum in the following patches.

(*) option to enable/disable HTTP/2 was in the same line as other nginx
    already jinja2'ified listen options.

    As already noted in f6f97d72 we are going to always support HTTP/2,
    that's why we do not merge-in upstream change only to through it away in
    the following patch.