Bug(?) in Python doctest

doctest_bug.py

#!/usr/bin/env python
# coding: utf-8

"""
The following test should pass, but it fails:

    >>> def spam():
    ...     print("eggs")
    ...
    >>> assert spam(), "Print 'eggs' before AssertionError"
    eggs
    Traceback (most recent call last):
        ...
    AssertionError: Print 'eggs' before AssertionError
"""


import doctest


if __name__ == "__main__":
    doctest.testmod()