(maint) provide a workaround for Psych::SyntaxError

In ruby 1.9.3 Psych::SyntaxError is a RuntimeException this still needs to
catch that and work also on rubies that do not have Psych available.

This was uncovered by the recent move to catch StandardError rather than the
catchall that was there before.

Author: DavidS

lib/puppet/parser/functions/parseyaml.rb

@@ -16,7 +16,10 @@ module Puppet::Parser::Functions
 
     begin
       YAML::load(arguments[0]) || arguments[1]
-    rescue StandardError => e
+      # in ruby 1.9.3 Psych::SyntaxError is a RuntimeException
+      # this still needs to catch that and work also on rubies that
+      # do not have Psych available.
+    rescue StandardError, (defined?(Psych::SyntaxError) ? Module.const_get('Psych::SyntaxError') : nil)  => e
       if arguments[1]
         arguments[1]
       else