There are other differences between Python 2.7 and Python 3. PR 4118 restores the Python 2.7 logic. It adds type checking, but its overhead is smaller.

$ ./python -m timeit 'from encodings import aliases'
500000 loops, best of 5: 542 nsec per loop

Actually in some cases (with '*') the new code is even slightly faster.

I don't know whether these differences were intentional, but all tests are passed.

The type of items in __all__ also is checked.