Yum lockfile is held by another process

[jamesmontalvo3]

Environment

• Machine or Virtual Machine details: Travis CI job #4
• Operating System: CentOS
• meza version hash: Many versions recently, perhaps since Ansible 2.8 release

Issue details

Intermittent errors on Travis CI job #4 (test_type = backup-to-remote). Error is:

TASK [base : ensure deltarpm is installed and latest] **************************
Monday 27 May 2019  23:34:52 +0000 (0:00:01.223)       0:00:22.767 ************
fatal: [172.17.0.2]: FAILED! => {
    "changed": false
}
MSG:
yum lockfile is held by another process
ok: [172.17.0.3]
ok: [localhost]

Note that this error is on 172.17.0.2, but not on 172.17.0.3 or localhost. localhost is, I believe, one of these two servers (172.17.0.2 or 172.17.0.3). If it is the failing server, then it's possible that localhost is already executing the task and has held the yum lockfile. The solution may be to add localhost to the exclude-all group, similar to the solution to #1035.

I thought the issue might have came from PackageKit, so I made #1164. The error is still happening though. I don't think we want PackageKit, so it doesn't hurt that #1164 explicitly removes it.

[jamesmontalvo3]

Link to error: https://travis-ci.org/enterprisemediawiki/meza/jobs/537995168#L1139-L1150

[jamesmontalvo3]

Ref: ansible/ansible#57189