title: Strange results from executeFetchRequest on iOS10
body: <p>I just ran into this issue where </p>
  
  <pre><code>+ (NSArray *)fetchMyStuffInContext:(NSManagedObjectContext *)_moc
  {
    NSFetchRequest  *request;
    NSPredicate     *pred;
    __block NSError *error;
    __block NSArray *myStuff;
  
    request = [[NSFetchRequest alloc] initWithEntityName:@"myobs"];
    pred    = [NSPredicate predicateWithFormat:@"anAttribute == YES"];
    [request setPredicate:pred];
  
    error   = nil;
    [_moc performBlockAndWait:^{
      myStuff = [_moc executeFetchRequest:request error:&amp;error];
    }];
    [request release];
  
    if (error) {
      NSLog(@"Error while fetching:\n%@",
        ([error localizedDescription] != nil) ?
          [error localizedDescription] : @"Unknown Error");
      return [NSArray array];
    }
  
    return myStuff;
  }
  </code></pre>
  
  <p>returns an array of IDs on iOS10 and an Array of managed objects on iOS9.</p>
  
  <p>iOS9 result <code>po myStuff</code>:</p>
  
  <pre><code>&lt;_PFArray 0x16589ee0&gt;(
    &lt;MyObj: 0x16589bb0&gt; (
      entity: myobs;
      id: 0xd000000000040000 &lt;x-coredata://81E85B5C-6504-4269-974B-5AB4449658DC/myobs/p1&gt; ;
      data: &lt;fault&gt;))
  </code></pre>
  
  <p>iOS10 result <code>po myStuff</code>:</p>
  
  <pre><code>&lt;__NSArrayM 0x170053e90&gt;(
      0xd000000000040000 &lt;x-coredata://81E85B5C-6504-4269-974B-5AB4449658DC/myobs/p1&gt;
  )
  </code></pre>
  
  <p>Why is that?</p>
  
  <p>On iOS 10, I can retrieve the object by calling</p>
  
  <pre><code>[moc objectWithID:]
  </code></pre>
  
  <p>What am I missing here?</p>