line 114: die "One of the postgres_targets_postgresSL_OT use flags must be enabled" this looks a bit weird and would maybe look better as: die "One of the postgres_targets_postgres_SLOT use flags must be enabled"
Not a typo, but yeah, it looks weird. Might be worth while to revise it further. How about: die "One of this ebuild's POSTGRES_TARGETS must be enabled, but isn't."