Like "cp -a" and "rsync -a" do, only report lchown errors if we run as root. Like cp from GNU coreutils does, we check Geteuid() to determine if we are running as root ( http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/copy.c#n3012 ). On Windows, lchown errors are always reported. Fixes https://github.com/restic/restic/issues/1766