Hello,
But I dug a hole for myself.4. Reinstall stretch's cups-browsed (no change in cupsd.conf) to go backto 2. "OpPolicy authenticated" is what I get! 5. Remove "DefaultPolicy authenticated" from cupsd.conf. Back to 1. Not at all! It's still "DefaultPolicy authenticated". Colour me perplexed (or inept).
I guess that some information is taken from the files in /var/cache/cups and that these cache files are not correctly updated ...
Regards Christoph