Unlike UFS, ZFS sets the uarch flag automatically whenever a file is modified. The test should be modified to explicitly clear it.
A commit references this bug: Author: asomers Date: Thu Dec 15 16:13:52 UTC 2016 New revision: 310118 URL: https://svnweb.freebsd.org/changeset/base/310118 Log: Fix ls_tests:o_flag with ZFS TMPDIR Unlike UFS or TMPFS, ZFS sets uarch automatically whenever a file is updated. The test must explicitly clear uarch to be portable across filesystems. Also, it doesn't need to run as root. PR: 215179 MFC after: 4 weeks Sponsored by: Spectra Logic Corp Differential Revision: https://reviews.freebsd.org/D8741 Changes: head/bin/ls/tests/ls_tests.sh
MFCed to stable/11 by r310118