> Not necessarily.  The fact that there is nothing to load doesn't
> mean it isn't the right loader if there *was* something to load.

But it is not even the right loader if there *was* something to load,
as get_filename() returns './foo.py' which is wrong even if
mypackage/foo.py had existed.  It should have returned
'./mypackage/foo.py' to be an acceptable loader for a would-be
mypackage.foo module.