Put 'main' test job back in python3 working section
Put 'main' test job back in python3 working section

It's been passing reliably since we upgraded to pytest 4.2.0

wagnerand/addons-server,eviljeff/olympia,bqbn/addons-server,bqbn/addons-server,mozilla/olympia,diox/olympia,mozilla/olympia,psiinon/addons-server,kumar303/addons-server,kumar303/olympia,mozilla/addons-server,wagnerand/addons-server,mozilla/addons-server,psiinon/addons-server,diox/olympia,diox/olympia,kumar303/addons-server,wagnerand/addons-server,kumar303/addons-server,kumar303/olympia,kumar303/olympia,wagnerand/addons-server,eviljeff/olympia,mozilla/olympia,eviljeff/olympia,mozilla/addons-server,kumar303/addons-server,mozilla/olympia,psiinon/addons-server,kumar303/olympia,bqbn/addons-server,diox/olympia,psiinon/addons-server,eviljeff/olympia,mozilla/addons-server,bqbn/addons-server