how is rosh's ok() different from rospy.is_shutdown()?

edit

Specifically, what's the difference with how they handle a KeyboardInterrupt/SIGINT?

I would expect these two snippets to act the same, but they don't:

#!/usr/bin/env python
import rospy
r = rospy.Rate(10)
while not rospy.is_shutdown():
    print 'ok...'
    r.sleep()

and

#!/usr/bin/env rosh
r = Rate(10)
while ok():
    print "ok..."
    r.sleep()

The first example exits on Ctrl+C, but the second does not. What am I missing?