downloader.rb: fix exception arguments

* tool/downloader.rb (Downloader.download): fix the exception to
  re-raise.  initialize methods of subclasses of Exception may
  have different parameters.  [ruby-core:67086] [Bug #10639]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48963 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Wed Dec 24 13:00:24 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* tool/downloader.rb (Downloader.download): fix the exception to
+	  re-raise.  initialize methods of subclasses of Exception may
+	  have different parameters.  [ruby-core:67086] [Bug #10639]
+
 Wed Dec 24 12:16:19 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ruby.h (rb_data_type_t): revert r48647 and revise parent member.

tool/downloader.rb

@@ -107,7 +107,7 @@ class Downloader
     end
     true
   rescue => e
-    raise e.class, "failed to download #{name}\n#{e.message}: #{url}", e.backtrace
+    raise "failed to download #{name}\n#{e.message}: #{url}"
   end
 end