Colourful terminal output has weird prefixes


#1

https://tools.taskcluster.net/groups/VpknNLzhREeVvuPjNdiatg/tasks/LnR9wjRoTLeJT58cct7JHg/runs/0/logs/public%2Flogs%2Flive.log shows a run which includes ansi terminal codes to add colour to the output. The lines with colour have weird prefixes appearing in the terminal.