* string.c (setup_fake_str): fake strings should not set class by
  RBASIC_SET_CLASS() because it insert write barriers to fake
  (non-RVALUE) structure.
  It can cause unexpected behaviour.
  Ruby 2.1 also have a same problem (setup_fake_str() in parse.y).
* symbol.c (setup_fake_str): ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47190 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* iseq.c (rb_iseq_clone): Should not insert write barrier from
  non-RVALUE data (to non-RVALUE data, of course).
  Ruby 2.1 also has a same problem.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47191 b2dd03c8-39d4-4d8f-98ff-823fe69b080e