A failed H2C upgrade causes an invocation failure when server sends 'Connection: close' header.

[trustin]

When an Armeria client sends the HEAD / upgrade request, some HTTP/1 servers send a 404 response with a Connection: close header instead of keeping the connection alive. The Armeria client attempts to send an HTTP/1 request for the current invocation to the closed connection after receiving the rejected upgrade response, which is incorrect and thus raises a SessionClosedException.

To fix this issue, we could make Armeria client handle Connection: close header properly and remember the list of the hosts that rejected the upgrade request.

(Originally reported by @anuraaga)

[trustin]

Should be fixed by #107

[trustin]

Fixed in 0.9.0.Final