This issue was very tricky to track down, but fortunately easy to fix.
The interaction here is subtle enough that it’s difficult to put into
English what would go wrong in what circumstances, but the new unit test
captures precisely that interaction to ensure it remains fixed.
This changes TableCoreCacheT to internally record dependencies at a
per-table level. In practice, this dramatically improves the performance
of building permissions: it makes it far, far less likely for
permissions to be needlessly rebuilt because some unrelated table
changed.