Fixed circular reference in OpPathPreview.
Fixed circular reference in OpPathPreview.

This was introduced in #812.

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