Escape language codes before matching them in case they contain

characters with special meaning in a regexp. Closes #2318.

vendor/plugins/http_accept_language/lib/http_accept_language.rb

@@ -49,7 +49,7 @@ module HttpAcceptLanguage
   def compatible_language_from(array)
     user_preferred_languages.map do |x|
       array.find do |y|
-        y.to_s =~ /^#{x.to_s}(-|$)/
+        y.to_s =~ /^#{Regexp.escape(x.to_s)}(-|$)/
       end
     end.compact.first
   end