downloader.rb: quote base name

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@67448 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/downloader.rb

@@ -88,7 +88,7 @@ class Downloader
           INDEX[:index] = IO.read index_file
         end
         file_base = File.basename(name, '.txt')
-        beta_name = INDEX[:index].match(/#{file_base}(-[0-9.]+d\d+)?\.txt/)[0]
+        beta_name = INDEX[:index][%/#{Regexp.quote(file_base)}(-[0-9.]+d\d+)?\.txt/]
         # make sure we always check for new versions of files,
         # because they can easily change in the beta period
         super(UNICODE_PUBLIC+name_dir_part+beta_name, name, dir, true, options)