Make an internal block of Generator return nil instead of self.

* lib/generator.rb (Generator#initialize): Make an internal block
  return nil instead of self. [Bug #7493]



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@38145 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2012-12-02

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@38146 b2dd03c8-39d4-4d8f-98ff-823fe69b080e