Implement smux transition
This does not include switching the handshake to JSON.
I'm rerunning the test that failed (nondeterministically) in #1758 to see if it still fails with smux. If so, we'll tackle it here.
This does not include switching the handshake to JSON.
I'm rerunning the test that failed (nondeterministically) in #1758 to see if it still fails with smux. If so, we'll tackle it here.