This was an oversight in 07bf378509. While it does reduce the benefit of the
simplification due to that commit, it still seems like a win to me.
It seems like it might be a good idea to have a function mirroring
InitPostmasterChild() / InitStandaloneProcess() for postmaster in miscinit.c
to make it easier to keep initialization between the three possible
environment in sync.
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210805214109.lzfk3r3ae37bahmv@alap3.anarazel.de
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