bug 1412891: Test compression middleware conflicts
bug 1412891: Test compression middleware conflicts

In Kuma we use both Brotli and GZip as compression algorithm depending
on browser support.

Double compression is prevented in the middleware, which is tested with
this commit.

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