win32/resolv.rb: ad hoc workaround

* ext/win32/lib/win32/resolv.rb (Win32::Resolv::SZ): an ad hoc
  workaround for broken registry.  SearchList and other registry
  values must be REG_SZ, or Windows ignores anything in those
  values otherwise.  [ruby-dev:49924] [Bug #13081]
  https://github.com/rubygems/rubygems/issues/1700

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57265 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/win32/lib/win32/resolv.rb

@@ -60,6 +60,21 @@ module Win32
 # Windows NT
 #====================================================================
   module Resolv
+    module SZ
+      refine Registry do
+        # ad hoc workaround for broken registry
+        def read_s(key)
+          type, str = read(key)
+          unless type == Registry::REG_SZ
+            warn "Broken registry, #{name}\\#{key} was #{Registry.type2name(type)}, ignored"
+            return String.new
+          end
+          str
+        end
+      end
+    end
+    using SZ
+
     TCPIP_NT = 'SYSTEM\CurrentControlSet\Services\Tcpip\Parameters'
 
     class << self