[Resolve Sceptre#1493] Complete DisableRollback implementation

This adds missing code to complete the implementation of the
DisableRollback feature.

The implementation in 99c839a is clear that it was intended that this
feature would cover both cases of creating and updating stacks, and this
code and unit test was missed.

sceptre/cli/update.py

@@ -41,6 +41,7 @@ def update_command(
     :type verbose: bool
     :param yes: A flag to answer 'yes' to all CLI questions.
     :type yes: bool
+    :param disable_rollback: A flag to disable cloudformation rollback.
     """
 
     context = SceptreContext(

sceptre/plan/actions.py

@@ -139,6 +139,10 @@ def update(self):
                     {"Key": str(k), "Value": str(v)} for k, v in self.stack.tags.items()
                 ],
             }
+
+            if self.stack.disable_rollback:
+                update_stack_kwargs.update({"DisableRollback": self.stack.disable_rollback})
+
             update_stack_kwargs.update(self.stack.template.get_boto_call_parameter())
             update_stack_kwargs.update(self._get_role_arn())
             response = self.connection_manager.call(

tests/test_actions.py

@@ -275,6 +275,42 @@ def test_update_sends_correct_request(self, mock_wait_for_completion):
             sentinel.stack_timeout, boto_response=ANY
         )
 
+    @patch("sceptre.plan.actions.StackActions._wait_for_completion")
+    @patch("sceptre.plan.actions.StackActions._get_stack_timeout")
+    def test_update_disable_rollback_overrides_on_failure(
+        self, mock_get_stack_timeout, mock_wait_for_completion
+    ):
+        self.actions.stack._template = Mock(spec=Template)
+        self.actions.stack._template.get_boto_call_parameter.return_value = {
+            "Template": sentinel.template
+        }
+
+        self.actions.stack.on_failure = "ROLLBACK"
+        self.actions.stack.disable_rollback = True
+
+        mock_get_stack_timeout.return_value = {"TimeoutInMinutes": sentinel.timeout}
+
+        self.actions.update()
+        self.actions.connection_manager.call.assert_called_with(
+            service="cloudformation",
+            command="update_stack",
+            kwargs={
+                "StackName": sentinel.external_name,
+                "Template": sentinel.template,
+                "Parameters": [{"ParameterKey": "key1", "ParameterValue": "val1"}],
+                "Capabilities": [
+                    "CAPABILITY_IAM",
+                    "CAPABILITY_NAMED_IAM",
+                    "CAPABILITY_AUTO_EXPAND",
+                ],
+                "RoleARN": sentinel.cloudformation_service_role,
+                "NotificationARNs": [sentinel.notification],
+                "Tags": [{"Key": "tag1", "Value": "val1"}],
+                "DisableRollback": True,
+            },
+        )
+        mock_wait_for_completion.assert_called_once_with(sentinel.stack_timeout, boto_response=ANY)
+
     @patch("sceptre.plan.actions.StackActions._wait_for_completion")
     def test_update_cancels_after_timeout(self, mock_wait_for_completion):
         self.actions.stack._template = Mock(spec=Template)