IIRC (and it's been a few years) the hook goes on sys.meta_path, which uses the HardenedModulesHook to load modules, but then the Python runtime binds the variable names and attributes and whatnot before returning import statements back to application code.
The python runtime does not appear to do this in the specific case of submodule attributes. Right now, the Python bug against this indicates that it is considered a documentation bug... but my hunch is that it's an actual bug. I'll try manually inserting the setattr() line into my local copy of the SDK and see how integration testing goes then.
What do you use for GAE python integration testing?
