assemble-parallel-streams causes timeouts

outcomwe analyser often fails reading assemble-parallel-streams. This log form the job contains several insanely long lines. The output is difficult for people to read and for software to analyse.

If the output of json2streams contained newlines instead of spaces, we would see fewer timeouts.
    http://reports.vapour.ws/releases/4081/job/assemble-parallel-streams/attempt/682