* lib/shellwords.rb (Shellwords#shellsplit): Fix the handling of
  the backslash in double quotes to conform to the standard.
  [ruby-core:63807] [Bug #10055]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56573 b2dd03c8-39d4-4d8f-98ff-823fe69b080e