Added spec on String#replace with strings having an invalid encoding.
Added spec on String#replace with strings having an invalid encoding.

eregon/rubyspec,sgarciac/spec,eregon/rubyspec,BanzaiMan/rubyspec,sgarciac/spec,jannishuebl/rubyspec,kachick/rubyspec,benlovell/rubyspec,bl4ckdu5t/rubyspec,ruby/rubyspec,ruby/spec,nobu/rubyspec,lucaspinto/rubyspec,ruby/spec,kidaa/rubyspec,wied03/rubyspec,askl56/rubyspec,ruby/spec,iliabylich/rubyspec,askl56/rubyspec,iliabylich/rubyspec,nobu/rubyspec,wied03/rubyspec,wied03/rubyspec,lucaspinto/rubyspec,yous/rubyspec,kidaa/rubyspec,nobu/rubyspec,BanzaiMan/rubyspec,eregon/rubyspec,kachick/rubyspec,ruby/rubyspec,bl4ckdu5t/rubyspec,sgarciac/spec,kachick/rubyspec,benlovell/rubyspec,jannishuebl/rubyspec,yous/rubyspec