FreeBSD 11.1 - unknown group wheel

[Vanco, Juraj]

Hello,

I am trying to build a kernel in FreeBSD 11.0, however I am getting a message

mtree -deU -f /usr/src/etc/mtree/BSD.usr.dist  -p /usr/obj/usr/src/tmp/usr >/dev/null
mtree: unknown group `wheel'
mtree: failed at line 6 of the specification
*** Error code 1


However the group is known:
# cat /etc/group | head -n 3
# $FreeBSD: releng/11.0/etc/group 294896 2016-01-27 06:28:56Z araujo $
#
wheel:*:0:root


and currently used:
# groups
0


Running any query on group result with zero answer:
# getent group wheel
#
# getent group video
#


Similar result gives mergemaster:
# mergemaster -p

*** The directory specified for the temporary root environment,
    /var/tmp/temproot, exists.  This can be a security risk if untrusted
    users have access to the system.

  Use 'd' to delete the old /var/tmp/temproot and continue
  Use 't' to select a new temporary root directory
  Use 'e' to exit mergemaster

  Default is to use /var/tmp/temproot as is

How should I deal with this? [Use the existing /var/tmp/temproot] d

   *** Deleting the old /var/tmp/temproot

*** Creating the temporary root environment in /var/tmp/temproot
 *** /var/tmp/temproot ready for use
 *** Creating and populating directory structure in /var/tmp/temproot

install: unknown group wheel


I cannot find if this is any known issue... Any clue?

jv
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