Remove stray instance variable to resolve serialization problem [#3769...

Remove stray instance variable to resolve serialization problem [#3769 state:resolved] (ht: Joe Rafaniello)

activesupport/lib/active_support/core_ext/time/marshal_with_utc_flag.rb

@@ -7,14 +7,20 @@ class << self
       alias_method :_original_load, :_load
       def _load(marshaled_time)
         time = _original_load(marshaled_time)
-        utc = time.instance_variable_get('@marshal_with_utc_coercion')
-        utc ? time.utc : time
+        time.instance_eval do
+          if defined?(@marshal_with_utc_coercion)
+            remove_instance_variable("@marshal_with_utc_coercion")
+            utc
+          else
+            self
+          end
+        end
       end
     end
 
     alias_method :_original_dump, :_dump
     def _dump(*args)
-      obj = frozen? ? dup : self
+      obj = dup
       obj.instance_variable_set('@marshal_with_utc_coercion', utc?)
       obj._original_dump(*args)
     end