Replacing a `decorator_list`

[MementoRC]

I encountered a situation where I want to remove some decorators (like replacing aiounittest.async_test with IsolatedAsyncioTestCase). refactor throws the InvalidActionError because it finds that I emptied the list of decorators, as it identified the decorator as critical. On the other hand, i don't want to delete the AsyncFunctionDef just because of the decorator_list
The workaround to that in my branch is to butcher the is_critical_node in order to invalidate the is_critical_node.
Would you suggest a neater way?