fuel-mirror sets too low priority on mos-holdback repository

[Miroslav Anashkin]

fuel-mirror is used to create local dpkg repos and to add those repos to local environments settings. Mirantis ships fuel-mirror with one configuration file: /usr/share/fuel-mirror/ubuntu.yaml

This file contain descriptions of two groups of repos: mos and ubuntu with their priorities. It turns out that those priorities are incorrect and we effectively break environment when we add local mirrors to its settings.

Steps to reproduce:

1. Add mos version to /etc/fuel-mirror/config.yaml: mos-version:8.0
2. Create local mirrors:
     fuel-mirror create -G mos ubuntu -P ubuntu
3. Add local mirrors to env's settings:
     fuel-mirror apply -G ubuntu mos \
       -I /usr/share/fuel-mirror/ubuntu.yaml \
       --replace --default

Expected result:
- Repos are added
- Correct priorities are configured

Actual result:
- repos are added
- incorrect priorities are configured

[Denis Meltsaykin (dmeltsaykin)]

Partial fix: https://review.openstack.org/#/c/444941/

[Ekaterina Shutova (eshutova)]

Verified on 9.2 mu1 updates.

Before mos-holdback priority was 1000 and doesn't exceed other repositories priority. With fix it has priority 1100 while other repos have priority 1050.

[Alexey Stupnikov (astupnikov)]

Won't Fix for 7.0-updates as we no longer support it.

[Alexey Stupnikov (astupnikov)]

8.0 patch: https://review.openstack.org/#/c/524226/

[Vladimir Jigulin (vjigulin)]

Verified on 8.0 + mu6 proposed
After steps from bug description:
- Without fix: mos, mos-updates, mos-security, mos-holdback priority = 1000
- With fix: mos, mos-updates, mos-security priority = 1050; mos-holdback priority = 1100