Arvados

Test run: https://ci.curoverse.com/job/developer-run-tests/111/ (test run 110 failed on sdk/python but didn't on my local run, so re-running to see if it was just a temporary issue)
Updated: 4115524460e89f36b99f2fb5de1adebd86daaf4a

Added a before_save filter to PipelineInstance model to update started_at and finished_at dates when changing states.

I think it would be good to ensure started_at isn't nil when changing state to Failed or Complete too, in case a client creates a new object with state=Complete.

I don't think it would affect anything in practice as things stand, but I think conceptually (and for the sake of our future selves) this should be before_validation rather than before_save -- e.g., if we were validating started_at and finished_at, we would want to validate after applying these defaults, not after.

other than those points, LGTM

Updates: 4f03b29b3efb42a48c3f397942d5b618b89390eb
Test running at https://ci.curoverse.com/job/developer-run-tests/114/

When the pipeline instances is finished (either completed or failed) and started_at is nil, it will have the exact same time as finished_at.