core: suppress one debugging log

core: suppress one debugging log

Otherwise, the log is shown even when getting properties.
Even though it is in the debug level, that's quite noisy.

[  338.785847] TEST-55-OOMD.sh[1624]: Oct 07 16:35:15 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.786985] TEST-55-OOMD.sh[1624]: Oct 07 16:35:17 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.787412] TEST-55-OOMD.sh[1624]: Oct 07 16:35:20 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.791776] TEST-55-OOMD.sh[1624]: Oct 07 16:35:22 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.792938] TEST-55-OOMD.sh[1624]: Oct 07 16:35:24 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.793225] TEST-55-OOMD.sh[1624]: Oct 07 16:35:26 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.793424] TEST-55-OOMD.sh[1624]: Oct 07 16:35:28 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.796448] TEST-55-OOMD.sh[1624]: Oct 07 16:35:31 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.797997] TEST-55-OOMD.sh[1624]: Oct 07 16:35:33 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount
[  338.799206] TEST-55-OOMD.sh[1624]: Oct 07 16:35:35 H systemd[1]: TEST-55-OOMD-testmunch.service: Unit not running in private mount namespace, cannot live mount