although we only chown if the build was requested by a local daemon
user. daemonless invocations will not chown as they do not have to.
remote builds *can* chown to the remote builder user, but that does
not seem to happen (for some reason keep-failed is not propagated).
Change-Id: Ic0ead406b38b4ca0556fec42d84888efa25123bf
eldritch horrors
ae3b8e58c3