PropertyRecordableMixin: clear _recorded_property_dict if empty

This makes smaller pickles

bt5/erp5_core_test/TestTemplateItem/portal_components/test.erp5.testPropertyRecordable.py

@@ -82,6 +82,7 @@ class TestPropertyRecordable(ERP5TypeTestCase):
     p.clearRecordedProperty('first_name')
     self.assertFalse(p.isPropertyRecorded('first_name'))
     self.assertTrue(p.isPropertyRecorded('last_name'))
+    self.assertTrue(hasattr(p, '_recorded_property_dict'))
 
     # clearing a property that is not currently recorded is not an error
     p.clearRecordedProperty('description')
@@ -89,5 +90,6 @@ class TestPropertyRecordable(ERP5TypeTestCase):
     p.clearRecordedProperty('last_name')
     self.assertFalse(p.isPropertyRecorded('first_name'))
     self.assertFalse(p.isPropertyRecorded('last_name'))
+    self.assertFalse(hasattr(p, '_recorded_property_dict'))
 
     p.clearRecordedProperty('description')

product/ERP5/mixin/property_recordable.py

@@ -87,6 +87,8 @@ class PropertyRecordableMixin:
     the property record.
     """
     self._getRecordedPropertyDict({}).pop(id, None)
+    if not self._getRecordedPropertyDict(True):
+      del self._recorded_property_dict
 
   security.declareProtected(Permissions.AccessContentsInformation,
                             'getRecordedPropertyIdList')