Description of problem:

Overcloud upgrade with system_upgrade tag fails if we pass '--limit Role name'

+++
2021-02-14 22:11:43,946 p=54900 u=mistral n=ansible | TASK [Force facts refresh after OS upgrade to refresh cache.] ******************
2021-02-14 22:11:43,946 p=54900 u=mistral n=ansible | Sunday 14 February 2021  22:11:43 -0500 (0:38:04.926)       1:07:17.610 *******
2021-02-14 22:11:43,990 p=54900 u=mistral n=ansible | skipping: [compute-101] => {"changed": false, "skip_reason": "Conditional result was False"}
2021-02-14 22:11:44,122 p=54900 u=mistral n=ansible | fatal: [compute-103]: FAILED! => {"changed": false, "module_stderr": "/bin/sh: /usr/bin/python: No such file or directory\n", "module_stdout": "", "msg": "The module failed to execute correctly, you probably need to set the interpreter.\nSee stdout/stderr for the exact error", "rc": 127}
2021-02-14 22:11:44,123 p=54900 u=mistral n=ansible | fatal: [compute-102]: FAILED! => {"changed": false, "module_stderr": "/bin/sh: /usr/bin/python: No such file or directory\n", "module_stdout": "", "msg": "The module failed to execute correctly, you probably need to set the interpreter.\nSee stdout/stderr for the exact error", "rc": 127}
+++

Found that the python library was missing. 

+++
[root@compute-102 heat-admin]# ls -lhtr /usr/bin/python
ls: cannot access '/usr/bin/python': No such file or directory
+++ 

And when we re-run the upgrade command with same command, but it just skips all tasks (likely since the nodes are already on RHEL8), and returns successful, but nothing gets updated/change.

Version-Release number of selected component (if applicable):
tripleo-ansible-0.5.1-1.20200914163930.el8ost.noarch

How reproducible:


Steps to Reproduce:
1. Run overcloud node leapp upgrade with --limit <role name>
2.
3.