registry.rb: try en_US message

* ext/win32/lib/win32/registry.rb (Win32::Registry::Error#initialize):
  try en_US message if the default message cannot be encoded to
  locale.  [ruby-core:65295] [Bug #10300]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48927 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/win32/lib/win32/registry.rb

@@ -175,11 +175,19 @@ For detail, see the MSDN[http://msdn.microsoft.com/library/en-us/sysinfo/base/pr
       def initialize(code)
         @code = code
         msg = WCHAR_NUL * 1024
-        len = FormatMessageW.call(0x1200, 0, code, 0, msg, 1024, 0)
-        msg = msg.byteslice(0, len * WCHAR_SIZE)
-        msg.delete!(WCHAR_CR)
-        msg.chomp!
-        super msg.encode(LOCALE)
+        lang = 0
+        begin
+          len = FormatMessageW.call(0x1200, 0, code, lang, msg, 1024, 0)
+          msg = msg.byteslice(0, len * WCHAR_SIZE)
+          msg.delete!(WCHAR_CR)
+          msg.chomp!
+          msg.encode!(LOCALE)
+        rescue EncodingError
+          raise unless lang == 0
+          lang = 0x0409         # en_US
+          retry
+        end
+        super msg
       end
       attr_reader :code
     end