rails/rails — pull request #6704 by amatsuda (2012-06-11 16:53:01+00:00)
Title: Proc always respond_to :binding

This if statement was introduced in 6ea4dd4a65f85f165f71cf1c866dea578dae9e49.
The comment says, "no Proc#binding in Ruby 2" in this commit, but the actual plan for Ruby 2 now is "100% compatible with Ruby 1.9.3" (Matz) http://vimeo.com/43590847