bug 1490727: Use one-liner mocks
bug 1490727: Use one-liner mocks

Use the return_value parameter to save a line of code. Nice find from
@michal-macioszczyk!

SphinxKnight/kuma,jwhitlock/kuma,mozilla/kuma,Elchi3/kuma,escattone/kuma,jwhitlock/kuma,a2sheppy/kuma,Elchi3/kuma,jwhitlock/kuma,escattone/kuma,Elchi3/kuma,a2sheppy/kuma,mozilla/kuma,SphinxKnight/kuma,mozilla/kuma,Elchi3/kuma,SphinxKnight/kuma,SphinxKnight/kuma,SphinxKnight/kuma,a2sheppy/kuma,SphinxKnight/kuma,a2sheppy/kuma,Elchi3/kuma,a2sheppy/kuma,jwhitlock/kuma,mozilla/kuma,mozilla/kuma,jwhitlock/kuma,escattone/kuma