title: What if the system time changes while I'm doing timed_wait with a duration?
body: <p>When using <code>timed_wait</code> on a <code>boost::condition_variable</code> with a duration, will the wait condition time out after the duration even if the user (or ntp) changes the system time?</p>
  
  <p>E.g.,</p>
  
  <pre><code>boost::posix_time::time_duration wait_duration(0, 0, 1, 0);  // 1 sec
  // ** System time jumps back 15 minutes here. **
  if( !signal.timed_wait(lock, wait_duration) )
  {
      // Does this condition happen 1 second later, or about 15 minutes later?
  }
  </code></pre>