[puppet4] incorrect repo priorities during bootstrap image building

[Nikita Karpin]

When deploying fuel master node with puppet4, it fails on building bootstrap image with errors:

Traceback (most recent call last):
  File "/usr/bin/fuel-bootstrap", line 10, in <module>
    sys.exit(main())
  File "/usr/lib/python2.7/site-packages/fuel_bootstrap/main.py", line 59, in main
    return FuelBootstrap().run(argv)
  File "/usr/lib/python2.7/site-packages/cliff/app.py", line 279, in run
    result = self.run_subcommand(remainder)
  File "/usr/lib/python2.7/site-packages/cliff/app.py", line 400, in run_subcommand
    result = cmd.run(parsed_args)
  File "/usr/lib/python2.7/site-packages/cliff/command.py", line 90, in run
    return self.take_action(parsed_args) or 0
  File "/usr/lib/python2.7/site-packages/fuel_bootstrap/commands/build.py", line 176, in take_action
    image_uuid, path = bs_image.make_bootstrap(vars(parsed_args))
  File "/usr/lib/python2.7/site-packages/fuel_bootstrap/utils/bootstrap_image.py", line 174, in make_bootstrap
    mngr.do_mkbootstrap()
  File "/usr/lib/python2.7/site-packages/fuel_agent/manager.py", line 1050, in do_mkbootstrap
    attempts=CONF.fetch_packages_attempts)
  File "/usr/lib/python2.7/site-packages/fuel_agent/utils/build.py", line 109, in run_apt_get
    stdout, stderr = utils.execute(*cmds, attempts=attempts)
  File "/usr/lib/python2.7/site-packages/fuel_agent/utils/utils.py", line 140, in execute
    stderr=stderr, cmd=command)
fuel_agent.errors.ProcessExecutionError: Unexpected error while running command.
Command: chroot /tmp/tmpQqgLv6.fuel-agent-image apt-get -y dist-upgrade
Exit code: 100
Stdout: 'Reading package lists...\n'
Stderr: 'E: No priority (or zero) specified for pin\n

Looks like puppet4 malformed priority settings in /etc/fuel-bootstrap-cli/fuel_bootstrap_cli.yaml:

repos:
- name: ubuntu
  section: main universe multiverse
  uri: http://archive.ubuntu.com/ubuntu
  priority: :undef
  suite: xenial
  type: deb
- name: ubuntu-updates
  section: main universe multiverse
  uri: http://archive.ubuntu.com/ubuntu
  priority: :undef
  suite: xenial-updates
  type: deb
- name: ubuntu-security
  section: main universe multiverse
  uri: http://archive.ubuntu.com/ubuntu
  priority: :undef
  suite: xenial-security
  type: deb

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/441197

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/441197
Committed: https://git.openstack.org/cgit/openstack/fuel-library/commit/?id=25bda8d2da8ce9785464c899024b88bba0017000
Submitter: Jenkins
Branch: master

commit 25bda8d2da8ce9785464c899024b88bba0017000
Author: Dmitry Ilyin <email address hidden>
Date: Fri Mar 3 19:06:39 2017 +0300

    Add undef2nil function

    Add a function which converts :undef values to nil values
    to solve the compatibility problems with puppet4.

    Apply this function to the bootstrap repository list.

    Related-Bug: 1668995
    Change-Id: Idfd793a1f8cc64361cb29d4b513e10c92da57151