When using autogenerated document ids in a sharded collection, do set that id back into the Document

tests/document/instance.py

@@ -2281,6 +2281,8 @@ class InstanceTest(unittest.TestCase):
         log.machine = "Localhost"
         log.save()
 
+        self.assertIsNotNone(log.id)
+
         log.log = "Saving"
         log.save()
 
@@ -2304,6 +2306,8 @@ class InstanceTest(unittest.TestCase):
         log.machine = "Localhost"
         log.save()
 
+        self.assertIsNotNone(log.id)
+
         log.log = "Saving"
         log.save()