* for version 0.264

* for version 0.263

* for version 0.262

* for version 0.261

* Improve _filter_old_dists by watching for order of additions

I was pretty stupid with the previous way I did this. I tracked
everything in %Seen, put returned the list to the next map anyway.
If the older dist showed up in the list first, I passed it on because
I hadn't seen anything newer yet. The list order matters.

I don't completely like how I've done it now, but it works.

* for version 0.20

* for version 0.19

* for version 0.17_03

* for version 0.17

* for version 0.15