Limit the scope of ReferenceGenome.invalidate_materialized_view().
Limit the scope of ReferenceGenome.invalidate_materialized_view().

We should use this pattern in other places where only a single field,
especially any kind of flag or boolean is being updated.

This doesn't resolve the concurrency issues that we realized we have,
but it significanlty reduces the chance that they pop up.

woodymit/millstone,woodymit/millstone_accidental_source,woodymit/millstone_accidental_source,woodymit/millstone,woodymit/millstone,woodymit/millstone_accidental_source,churchlab/millstone,woodymit/millstone_accidental_source,churchlab/millstone,woodymit/millstone,churchlab/millstone,churchlab/millstone