Invalidating ghost cells in Nebo
We planned and designed Nebo to invalidate ghost cells that it cannot populate with valid results because of stencil operations. However, invalidating these ghost cells breaks regression tests for pretty much any test that uses stencils.
Thus Nebo currently does NOT invalidate ghost cells.
We need to change this and update all tests that fail as a result.
This is currently implemented on the invalid-ghost
branch, but needs cleanup & merge.
See also #7 , which is closely related to this issue.