Code review comment for lp://qastaging/~tpatil/nova/bug708822

Just as a suggestion, I find long if statements difficult to read. Would it be possible to give these two values relevant names, something like:

min_delta = datetime.timedelta(seconds=-FLAGS.service_down_time)
max_delta = datetime.timedelta(seconds=FLAGS.service_down_time)

...which would turn the if into something like:

if min_delta < delta < max_delta: