create database name with location = 'path'; - Mailing list pgsql-hackers

I have ALLOW_ABSOLUTE_DBPATHS enabled. but it does not do what one would
assume.

template1=# create database fubar with location = '/tmp'  ;
ERROR:  CREATE DATABASE: could not link '/postgres/data/base/12523613' to
'/tmp/base/12523613': Operation not permitted

Is this telling me it is creating the database as it always does, but is
linking it to the specified location ?

If so, what's the point of this?