CMFActivity: Make "flush" support ActivityRuntimeEnvironment.

This is a very minimal support, as "flush" is kind of deprecated, only
surviving because tests need to be able to tell which activity may
execute, and there is currently no other way to support this.

product/CMFActivity/Activity/SQLBase.py

@@ -677,7 +677,8 @@ class SQLBase(Queue):
                          message.validate(self, activity_tool)
         if validate_value == VALID:
           # Try to invoke the message - what happens if invoke calls flushActivity ??
-          activity_tool.invoke(message)
+          with ActivityRuntimeEnvironment(message):
+            activity_tool.invoke(message)
           if message.getExecutionState() != MESSAGE_EXECUTED:
             raise ActivityFlushError('Could not invoke %s on %s'
                                      % (message.method_id, path))