run_check truncate -s0 img
chmod a+w img
run_check truncate -s2g img
loopdev=`run_check_stdout $SUDO_HELPER losetup --find --show img`
run_check truncate -s0 img
chmod a+w img
run_check truncate -s2g img
loopdev=`run_check_stdout $SUDO_HELPER losetup --find --show img`