in What's New for 5.1.

This was the rollback of the fix for #1206 brought about in #2042.

Remains of copy/pasta made that v2 listened with PROXY protocol which is
not needed. It's a passive instance that only does health checking using
a probe.

not as smart as LLVM about const.

I guess if you can't say anything else good about it, H2 is forcing
me to invent new ways to implement table-driven object-oriented programming.

which per-frame flags only get sent on the last frame of a
continued frame-sequence.

This rolls back the fix for #1206 -- the decision is made regardless
of the pass state of the backend fetch. So delivery sets resp.status
to 304 at ESI level 0 iff the conditions in req.http.{INM,IMS} and
resp.http.{ETag,Last-Modified} allow it. To restore the behavior
from #1206, remove the If-* headers in vcl_pass.

Fixes #2042

Fixes #2151

It consists in the source and destination being the same socket address.

Refs #2151

Fixes #2217

Jail contortions.

Fixes #2245

Fixes #2227

Please fill in the rest! This first draft has content that I know about:
* The return of hit-for-pass
* Changes in VRT and libvarnishapi

Make sure Age is always less than max-age