Did I just find a bug in python locks? Or do I simply don't understands them? Signals does not wake up main thread if waiting with an indefinite time

signaltest.py

"""
When `wait` is None, program does not receive signal (and cannot be stopped)
When anything else, signals wakes up main thread and stop as intended

"""
import os
import signal
from threading import Event


lock = Event()

def sighandler(signum, frame):
    print 'got signal %d' % signum
    lock.set()
signal.signal(signal.SIGTERM, sighandler)
signal.signal(signal.SIGINT, sighandler)

print 'Start with pid %d' % os.getpid()

wait = 10
while not lock.wait(wait):
    print 'waited %r seconds' % wait

print 'done'