Frustratingly the latest pycairo / pygobject release have completely broken the build process - see https://github.com/Oxygem/Kanmail/tree/fix-linux-builds.

AND the huge (>60mb) builds have returned, so that also needs investigation.

Once something is working again, will publish the underlying Docker images so such changes don't break future builds, similar to the frozen MacOS10.10 build env.