libcurl, we may introduce a way to bring such clues to the applicaton and/or
let a subsequent request use the alternate route
automatically. [Spec](https://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-14)
-
-TODO
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-
- - Implement "prior-knowledge" HTTP/2 connections over clear text so that
- curl can connect with HTTP/2 at once without 1.1+Upgrade.
To decide: if we need to bundle parts of the nghttp2 stuff that probably
won't be shipped by many distros.
-- provide option for HTTP/2 "prior knowledge" over clear text
-
- As it would avoid the roundtrip-heavy Upgrade: procedures when you _know_
- it speaks HTTP/2.
-
HTTP cookies
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