The side-band status report can be sent at the same time as the
primary payload multiplexed, but the demultiplexer on the receiving
end incorrectly split a single status report into two, which has
been corrected.
* js/avoid-split-sideband-message:
test-pkt-line: drop colon from sideband identity
sideband: report unhandled incomplete sideband messages as bugs
sideband: avoid reporting incomplete sideband messages