Merge branch 'jt/http-auth-proto-v2-fix'

Unify RPC code for smart http in protocol v0/v1 and v2, which fixes a bug in the latter (lack of authentication retry) and generally improves the code base. * jt/http-auth-proto-v2-fix: remote-curl: use post_rpc() for protocol v2 also remote-curl: refactor reading into rpc_state's buf remote-curl: reduce scope of rpc_state.result remote-curl: reduce scope of rpc_state.stdin_preamble remote-curl: reduce scope of rpc_state.argv