Only respond on noflo subprotocol when specified
Only respond on noflo subprotocol when specified

Fixes a rare exception when UI attempts to connect without
subprotocol after having tried noflo and it failed.

microflo/microflo,microflo/microflo,rraallvv/microflo,microflo/microflo,microflo/microflo,rraallvv/microflo,microflo/microflo,rraallvv/microflo,microflo/microflo,rraallvv/microflo