fix PATH environ related test failure introduced at r41873

On Windows PATH_SEPARATOR is ';'.
Therefore it can't be hardcoded.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41892 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rubygems/test_gem_commands_environment_command.rb

@@ -11,7 +11,7 @@ class TestGemCommandsEnvironmentCommand < Gem::TestCase
 
   def test_execute
     orig_sources = Gem.sources.dup
-    orig_path, ENV['PATH'] = ENV['PATH'], '/usr/local/bin:/usr/bin:/bin'
+    orig_path, ENV['PATH'] = ENV['PATH'], %w[/usr/local/bin /usr/bin /bin].join(File::PATH_SEPARATOR)
     Gem.sources.replace %w[http://gems.example.com]
     Gem.configuration['gemcutter_key'] = 'blah'