It happens because geoshape service doesn't expect the header application/sparql-results+json;charset=utf-8. There is a new PR in progress but needs more tests to make sure the changes works properly on the jessie instances since we have some work related strictly to the stretch migration.
Deployed a temporary fix and the examples above are now working. Downgrading the priority from UBN accordingly. I'll leave the ticket open until this has been fixed properly in kartotherian/geoshapes.