Deal with provider.open edge case in new provider-agnostic tests. Fixes issue #127

This test isn't really necessary anymore, and we already test it elsewhere in the providers.  With the new provider swapping in the test harness, it's impossible to test this easily and not know which provider you have.  I've removed the test that was failing and documented the issue.  It's actually only a problem with IndexedDB and the way we open the db, but it's not a bug.