Comment 9 for bug 660174

So, standard python module getpass.py has this function

def getuser():
    """Get the username from the environment or password database.

    First try various environment variables, then the password
    database. This works on Windows as long as USERNAME is set.

    """

    import os

    for name in ('LOGNAME', 'USER', 'LNAME', 'USERNAME'):
        user = os.environ.get(name)
        if user:
            return user

    # If this fails, the exception will "explain" why
    import pwd
    return pwd.getpwuid(os.getuid())[0]

Of course in the case of windows service there is no USERNAME, so that function will fall to import pwd.