Error while updating grub menu via pfexec?

Despite the diagnostic messages, I've got concerned if that could have damaged my grub.cfg as a side-effect.

$ bootadm set-menu timeout=15

bootadm: you must be root to run this command

$ pfexec bootadm set-menu timeout=15

Traceback (most recent call last):

  File "/usr/lib/python2.6/vendor-packages/bootadm-helper.py", line 368, in bootadm_set_menu

    splashimage='boot/background.png', indexstr='2,4')

  File "/usr/lib/python2.6/vendor-packages/bootadm-helper.py", line 72, in _bootadm_commit_menu

    ''' Get the mountpoint the root pool is mounted at. This function is

  File "/usr/lib/python2.6/vendor-packages/bootmgmt/bootconfig.py", line 641, in commit_boot_config

    ': Migration is not \