delete a check on bad assumption.
delete a check on bad assumption.

If object was modified, but there is a case that
hash values (#hash) are same between before modified
and after modified objects.

eregon/rubyspec,ruby/spec,ruby/spec,eregon/rubyspec,nobu/rubyspec,nobu/rubyspec,eregon/rubyspec,nobu/rubyspec,ruby/spec