Alt-Svc-bis / rfc7838bis

As discussed on this list earlier this year, there is growing reason
to start on an alt-svc-bis to update rfc7838.  I started a document
here outlining some potential candidates for inclusion and have incorporated
input from a number of people:

https://docs.google.com/document/d/1QNaXduqohACK93qLPpxkPJ2rHQMgWqUPL-DkZS11htQ/edit?ts=60a5dc92#

(There is a snapshot of this google doc posted as
draft-nygren-altsvc-fixes-00
for posterity as well.)

There will hopefully be some time at the interim next week to discuss
in more detail.  There are a number of design decisions that will likely
want discussion before we get too deep into authoring changes.

For example, one open question is whether to add an ALTSVC frame to QUIC
or whether to deprecate the ALTSVC frame in HTTP/2 instead.  The latter
seems to have some traction.

Mike Bishop started a repo with a markdown version of rfc7838
as a starting point:  https://github.com/MikeBishop/alt-svc-bis

Preliminary slides for next week are here:

https://docs.google.com/presentation/d/180QqdkL_hsKcdEroZkgZuxKPaybOBolWHd8BcQFSXMI/edit#slide=id.gdd99711ec5_0_33

Best, Erik