Root chowns a directory to the number its owner's setting names, so a key
an owner asks for must not change through the settings verb: any caller
could have set puid to 0 or to its own uid. TerminalKeys now takes every
${setting:…} in a directory's owner, whatever else asks for it, and the
owner is written as the parsed number so "0001" never reaches the
node-engine as text (review 60).