described_class behavior doesn't make sense when inner block is not a Class

Gemfile:
gem 'rspec', '= 3.0.0'

spec/described_class_spec.rb:

describe Array do
  describe 'a string' do
     it { expect(described_class).to eq(Array) }
  end

  describe :a_symbol do
    it { expect(described_class).to eq(Array) }
  end

  describe Hash do
    it { expect(described_class).to eq(Hash) }
  end

  describe Hash.new do
    it { expect(described_class).to eq(Hash) }
  end
end

This results in two errors--one on :a_symbol and one on Hash.new. IMO this behavior is non-intuitive. rspec/rspec-core#1114 seems to have made an exception for when the inner describe is an instance of String, which makes sense, because described_class.should be_a(Class). However, I argue that this should be consistent for all cases where the inner describe is not a Class. Either take its class, or skip it and move to the outer describe block, but don't return an instance.

Start with spec/described_class_spec.rb and reproduce the failures for the symbol and Hash.new nested descriptions. Read the existing described_class behavior and related examples to determine the intended consistent handling of non-Class inner descriptions. Done means the chosen behavior is covered by passing focused specs without returning an instance unexpectedly.