rspec/rspec-core — pull request #1492 by postmodern (2014-04-18 00:28:01+00:00)
Title: Ensure the same version of rspec is executed.

* If a developer is not using bundler, but specifies the desired version of rspec via `gem 'rspec', '~> 2.10.0'`, than the version of rspec that the rake task executes should match that of the loaded rspec-core.