it/s display is wrong

[CGamesPlay]

Hello, I was misled by tqdm 0.7.0 in some recent experiments, so I'm filing this discovery as a bug. Here's a sample of 4 bars from my code. In all of them, the computed it/s is wrong. These were made using the Iter::tqdm() function.

100%|███████| 100/100 [00:34<00:00, 2.10it/s]
100%|███████| 100/100 [00:43<00:00, 8.05it/s]
100%|███████| 100/100 [00:32<00:00, 2.07it/s]
100%|███████| 100/100 [00:43<00:00, 42.21it/s]

I suspect that tqdm is trying to show some sort of "recent speed", but failing to update the final result with overall aggregates, but I can't be sure.

As a quick side note, I also noticed that it's not possible to set the description of a manually-created Pbar (only Tqdm, which requires an Iterator).