Unit tests fail now without Nextstrain metadata archives #182
Description
After starting a PR to fix the historical metadata loss issue, we now don't have the data used in some unit tests of CladeTime (!)...
This issue stems from and is also summarized in the VNH (a recent PR summary and an issue).
We'll need to amend these unit tests (I think) in order to make the relevant historical metadata loss changes for a long-term fix.