cga-harvard/cga-worldmap — comment on commit 4bbd830715bb92214dcd9fb87ae992b1023b9985
File: src/GeoNodePy/geonode/maps/models.py line 1228
By mbertrand:

The url may often be blank, so it has to be unique only when not empty. There's some javascript in GeoExplorer that tries to enforce this when saving a map but there should probably also be some django code to check uniqueness again before saving.