Fixed Exception.to_yaml to output the backtrace.

Fixed Exception.yaml_new to properly load the message and backtrace.
Added test to ensure an Exception remains the same both sides of a yaml conversion.

ext/ruby/lib/yaml/rubytypes.rb

@@ -159,17 +159,29 @@ def to_yaml( opts = {} )
 
 class Exception
     yaml_as "tag:ruby.yaml.org,2002:exception"
+
+    # override exc_equal(), since it fails somehow, although message, backtrace and class are all equal.
+    def == obj
+        return false unless self.backtrace == obj.backtrace
+        return false unless self.message == obj.message
+        return false unless self.kind_of?(obj.class) || obj.kind_of?(self.class) # transitive
+        true
+    end
+
     def Exception.yaml_new( klass, tag, val )
-        o = YAML.object_maker( klass, { 'mesg' => val.delete( 'message' ) } )
+        o = eval("#{klass}.new(\"#{val.delete('message')}\")")
+        o.set_backtrace(val.delete('backtrace'))
+
         val.each_pair do |k,v|
-            o.instance_variable_set("@#{k}", v)
+          o.instance_variable_set("@#{k}", v)
         end
         o
     end
 	def to_yaml( opts = {} )
-		YAML::quick_emit( object_id, opts ) do |out|
+		YAML::quick_emit( self, opts ) do |out|
             out.map( taguri, to_yaml_style ) do |map|
                 map.add( 'message', message )
+                map.add( 'backtrace', backtrace )
 				to_yaml_properties.each do |m|
                     map.add( m[1..-1], instance_variable_get( m ) )
                 end

ext/ruby/tests/basic.rb

@@ -1651,6 +1651,16 @@ def test_time_now_cycle
     #        inspect_str = "[[...], [...]]"
     #        assert_equals( inspect_str, YAML::load( a.to_yaml ).inspect )
     #    end
+
+    #
+    # Test Exception
+    #
+    def test_exception
+        require 'yaml'
+        e1 = Exception.new("hello")
+        e1.set_backtrace(["file1.rb", "file2.rb"])
+        assert_equals(e1, YAML.load( YAML.dump( e1 ) ) )
+    end
 end
 
 RUNIT::CUI::TestRunner.run( YAML_Unit_Tests.suite )