I wrote:
> So I'm toying with the idea of extending Andrew's patch to put a negative
> preference on "localtime", ensuring we'll use some other name for the zone
> if one is available.
Oh ... after further review it seems like "posixrules" should be
de-preferred on the same basis: it's uninformative and unportable,
and it's short enough to have a good chance of capturing initdb's
attention. I recall having seen at least one machine picking it
recently.
Moreover, while I think most tzdb installations have that file (ours
certainly do), the handwriting is on the wall for it to go away,
leaving only postmaster startup failures behind:
http://mm.icann.org/pipermail/tz/2019-June/028172.html
regards, tom lane