I wrote: > So the problem is precisely that *our* interpretation of EST5EDT > changed when we adopted tzdata 2024b, and that is affecting how > we dump these old timestamps. Or at least, that seems like what > should be happening, but then why is only crake showing a failure?
Oh, got it: of the machines in question, only crake is selecting EST5EDT as default timezone. I can see from the buildfarm logs that drongo and fairywren are using UTC, and as said, my test instance is selecting America/New_York. Both UTC and America/New_York would have rendered these old timestamps the same way all along, but EST5EDT just changed its interpretation of them.
That means that simply forcing a re-run of the old branches on crake won't fix it, because pre-v12 branches will still think that EST5EDT means what it used to. We need to make sure that the dumps are taken in a completely stable zone, i.e. UTC.
Yep, I rebuilt all those old branches using 'America/New_York" and we're back to green. Thanks for the diagnosis.
