5.3 Rearrange request header order
5.4 Allow SAN names in HTTP/2 server push
5.5 auth= in URLs
+ 5.6 alt-svc should fallback if alt-svc doesn't work
6. TELNET
6.1 ditch stdin
Additionally this should be implemented for proxy base URLs as well.
+5.6 alt-svc should fallback if alt-svc doesn't work
+
+ The alt-svc: header provides a set of alternative services for curl to use
+ instead of the original. If the first attempted one fails, it should try the
+ next etc and if all alterantives fail go back to the original.
+
+ See https://github.com/curl/curl/issues/4908
6. TELNET