* eval.c (error_print): should no call "to_str" anymore use
  "message" method instead.

* io.c (rb_f_open): Kernel#open() calls "to_open" if the first
  argument responds to it. [Ruby2]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@6102 b2dd03c8-39d4-4d8f-98ff-823fe69b080e