Ruby

parse.y: keep literal encoding

• parse.y (literal_concat_gen, evstr2dstr_gen): keep literal
  encoding beginning with an interpolation same as the source file
  encoding. [ruby-core:70703] [Bug #11519]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51820 b2dd03c8-39d4-4d8f-98ff-823fe69b080e