I am fairly certain that at this point all that the mutators are doing is adding some metadata related to repl.  there's no conceivable reason that they should be altering index specs.  That said, I think that since we can expect the same vclock and index data for both, that it shouldn't matter, but that using `MaybeFake` is likely more correct.

This makes me wonder about that `hashtree_update()` call as well, shouldn't it be using `MaybeFake`?