when the following failure is thrown
```
rhel-8.0.0-beta-1.7- [=== ] --- B/s | 0 B --:-- ETArhel-8.0.0-beta-1.7-appstream 0.0 B/s | 0 B 00:00
rhel-8.0.0-beta-1.7- [=== ] --- B/s | 0 B --:-- ETArhel-8.0.0-beta-1.7-baseos 0.0 B/s | 0 B 00:00
rhel-8.0.0-beta-1.7- [ === ] --- B/s | 0 B --:-- ETArhel-8.0.0-beta-1.7-builder 0.0 B/s | 0 B 00:00
Failed to synchronize cache for repo 'rhel-8.0.0-beta-1.7-appstream', ignoring this repo.
Failed to synchronize cache for repo 'rhel-8.0.0-beta-1.7-baseos', ignoring this repo.
Failed to synchronize cache for repo 'rhel-8.0.0-beta-1.7-builder', ignoring this repo.
No match for argument: python3
Error: Unable to find a match
```
dnf returns 0 anyway.
Let's ensure the pattern 'Failed' isn't present in the output.
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
to avoid duplicating code in `site.yml.sample`, `site-docker.yml.sample`
and `setup.yml`, let's isolate this part of the code and simply include
it each time we need it.
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>