Added failing test for Group.
Added failing test for Group.

This exposes the bug which is the root cause of #179.

johnhaddon/gaffer,appleseedhq/gaffer,paulondc/gaffer,cedriclaunay/gaffer,hradec/gaffer,GafferHQ/gaffer,goddardl/gaffer,lucienfostier/gaffer,cedriclaunay/gaffer,boberfly/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,davidsminor/gaffer,cedriclaunay/gaffer,lucienfostier/gaffer,boberfly/gaffer,davidsminor/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,johnhaddon/gaffer,davidsminor/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,boberfly/gaffer,hradec/gaffer,chippey/gaffer,appleseedhq/gaffer,paulondc/gaffer,andrewkaufman/gaffer,boberfly/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,hradec/gaffer,hradec/gaffer,goddardl/gaffer,ivanimanishi/gaffer,hradec/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,paulondc/gaffer,paulondc/gaffer,ImageEngine/gaffer,davidsminor/gaffer,chippey/gaffer,andrewkaufman/gaffer,goddardl/gaffer,andrewkaufman/gaffer,cedriclaunay/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,chippey/gaffer,ImageEngine/gaffer,appleseedhq/gaffer,chippey/gaffer,ImageEngine/gaffer,goddardl/gaffer,johnhaddon/gaffer