Fuel 6.0 failed bootstrap admin node

VERSION:
  feature_groups:
    - mirantis
    - experimental
  production: "docker"
  release: "6.0"
  api: "1.0"
  build_number: "58"

We encountered bootstrap admin node failure, error reported in /var/log/puppet/bootstrap_admin_node.log
/////LOG/////
Error: Could not run: Could not find file /etc/puppet/modules/nailgun/examples/host-only.pp^[[0m
rmdir: failed to remove `/var/log/remote': No such file or directory
/usr/local/sbin/bootstrap_admin_node.sh: line 82: dockerctl: command not found
ERROR: Fuel node deployment FAILED! Check /var/log/puppet/bootstrap_admin_node.log for details
 /////////

Then we found in anaconda-post-after-chroot.log
/////LOG/////
+ SOURCE=/tmp/source
+ FS=/tmp/fs
++ cat /tmp/source/openstack_version
cat: /tmp/source/openstack_version: No such file or directory
+ OPENSTACK_VERSION=
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ROOT CAUSE:
In ks.cfg starting from line 360, we found post configure script is trying to get 'OPENSTACK_VERSION' before mount usb stick.
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SOURCE=/tmp/source
FS=/tmp/fs

OPENSTACK_VERSION=`cat ${SOURCE}/openstack_version`

echo
mkdir -p ${SOURCE}
mkdir -p ${FS}

if test -e /dev/disk/by-uuid/e8d3b51e-20c0-4d4c-982a-33c00a3ffc00; then
    mount /dev/disk/by-uuid/e8d3b51e-20c0-4d4c-982a-33c00a3ffc00 ${FS}
    mount -o loop ${FS}/nailgun.iso ${SOURCE}
fi
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So that 'OPENSTACK_VERSION' will be empty, then script will try to decompress puppet module file to non-exist folder incorrectly. This will leading to report error logs above and cause bootstrap failed.
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mkdir -p /etc/puppet/${OPENSTACK_VERSION}/manifests/
mkdir -p /etc/puppet/${OPENSTACK_VERSION}/modules/
rm -rf /etc/puppet/modules/

# TODO(ikalnitsky): investigate why we need this
cp ${SOURCE}/puppet-slave.tgz ${wwwdir}/

# place modules and manifests
tar zxf ${SOURCE}/puppet-slave.tgz -C /etc/puppet/${OPENSTACK_VERSION}/modules
/////////