DUB: "Invalid source/import path"

[Ivan Trombley via Digitalmars-d-dwt]

If I use DWT 3.0.0 as a dependency in my dub.json then DUB 
reports "Invalid source/import path" for 
~/.dub/packages/dwtlib-3.0.0/dwtlib/dwt/src and 
~/.dub/packages/dwtlib-3.0.0/dwtlib/dwt/views.

Any ideas?