739b872f6c
Be a little more vocal about the risks of remote collations not matching local ones. Actually fixing these risks seems hard, and I've given up on the idea that it might be back-patchable. So the best we can do for the back branches is add documentation. Per discussion of bug #16583 from Jiří Fejfar. Discussion: https://postgr.es/m/2438715.1632510693@sss.pgh.pa.us