Python module shadowing

datetime.py

# Call this file "datetime.py" (or any other stdlib name)
# and import it. It will behave just as if it was the
# library itself, but contain a 'fake' attribute

# $ ls
# datetime.py
# $ python
# >>> import datetime
# >>> datetime.fake
# True
# >>>

import sys
__builtins__['n'] = __name__
sys.path.remove('')
sys.modules.pop(n)
obj = __import__(n)
vars(obj)['fake'] = True
__builtins__.pop('n')