After looking into this, I think Alexander is correct. There is no
standard mapping between __file__ and __name__ and linecache is mistaken
in assuming such a mapping exists for all importers (and is the same as
the standard filesystem to name mapping to boot).

In this particular case, it was the differences between the way the two
relate for a package vs a normal module that was confusing linecache,
but for more exotic cases the filesystem based rules that linecache was
attempting to enforce may be completely irrelevant.