Add an additional spec for the first from #1580.

Created by: myronmarston

The spec added in #1580 is a bit implicit in that it depends upon RbConfig issuing a warning, which may not always be the case in all versions of ruby. The basic problem is that we were not ignoring top level constants, so this added spec makes that more explicit, and we can count on Hash always being a top level constant even if RbConfig doesn’t always issue the warning.