the only binary of src:pencil has been took over by pencil2d as a transitional measure.
pencil is nowadays orphaned, quite broken, and upstream does not exist anymore since years, while pencil2d is its maintained fork.
so, please remove the pencil2d source (there should be no binaries left) from xenial. afaik there should be no reverse (build-)depends.
the only binary of src:pencil has been took over by pencil2d as a transitional measure.
pencil is nowadays orphaned, quite broken, and upstream does not exist anymore since years, while pencil2d is its maintained fork.
so, please remove the pencil2d source (there should be no binaries left) from xenial. afaik there should be no reverse (build-)depends.