allow setting of a demodulized class name when using STI

If your STI class looks like this:

```ruby
class Company < ActiveRecord::Base
  self.store_full_sti_class = false

  class GoodCo < Company
  end

  class BadCo < Company
  end
end
```

The expectation (which is valid) is that the `type` in the database is saved as
`GoodCo` or `BadCo`. However, another expectation should be that setting `type`
to `GoodCo` would correctly instantiate the object as a `Company::GoodCo`. That
second expectation is what this should fix.

1 files changed, 3 insertions, 0 deletions

diff --git a/activerecord/test/models/company.rb b/activerecord/test/models/company.rb
index 6961f8fd6f..67936e8e5d 100644
--- a/activerecord/test/models/company.rb
+++ b/activerecord/test/models/company.rb
@@ -26,6 +26,9 @@ class Company < AbstractCompany
   def private_method
     "I am Jack's innermost fears and aspirations"
   end
+
+  class SpecialCo < Company
+  end
 end
 
 module Namespaced