When a refinement level is regridded, the outer region (ghost zones and boundaries) are invalidated, but PreSync validities are not properly updated to reflect this. A pull request has been created. It still needs to also detect whether the grid functions are prolongated or not. If they aren’t, they should be set to `nowhere' instead of `interior'.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2657/carpet-regrid-does-not-set-validities-for