rails/rails — pull request #8592 by rafaelfranca (2012-12-23 23:34:09+00:00)
Title: Remove warning of intance variable not initialized

I'm not sure if this is the best fix.

@tenderlove chould you review this one?

```
activesupport/lib/active_support/core_ext/thread.rb:68: warning:
instance variable @locals not initialized
```