Log Message:
Update ruby-rspec-mocks to 2.12.2.

### 2.12.2 / 2013-01-27
[full changelog](http://github.com/rspec/rspec-mocks/compare/v2.12.1...v.2.12.2)

Bug fixes

* Fix `and_call_original` to work properly for methods defined
  on a module extended onto an object instance (Myron Marston).
* Fix `stub_const` with an undefined constnat name to work properly
  with constant strings that are prefixed with `::` -- and edge case
  I missed in the bug fix in the 2.12.1 release (Myron Marston).
* Ensure method visibility on a partial mock is restored after reseting
  method stubs, even on a singleton module (created via `extend self`)
  when the method visibility differs between the instance and singleton
  versions (Andy Lindeman).