Tom Lane:
Also, as a real place to a greater extent than "PST8PDT" is, it's more subject to historical revisionism when somebody turns up evidence of local law having been different than TZDB currently thinks.
I now tried all versions of tzdata which we had in tree back to 2018g, they all work fine with the same regression test output. 2018g was an arbitrary cutoff, I just didn't try any further.
In the end, we don't need a default timezone that will never change. We just need one that didn't change in a reasonable number of releases going backwards. Once America/Los_Angeles is changed, we need to switch to a different zone, which could be one that wouldn't work today. Kind of a sliding window.
One positive might be: With this timezone, we are more likely to see relevant changes mentioned in the upstream release notes.
Best, Wolfgang
