@joshvfleming given the confusing semantics of `incr :hello, create: true`, this spec makes me a little uneasy.  It seems to suggest that we *won't* delete a key that was merely incremented, but not created via increment, which I don't think is true as implemented.

As this is intended for testing, I think the implemented behaviour is actually the desired behaviour (we'll delete any INCR'd key, whether or not INCR created it).  So I think all I'd change is to add another spec for that case.