Since the ansible collections ansible-collection-ansible-netcommon and ansible-collection-community-general are installed from OSP repo as defined in https://github.com/openshift/installer/pull/8830, the 4.15 UPI playbooks are failing:

network.yaml playbook -

TASK [Create the cluster IPv4 subnet] ******************************************
fatal: [localhost]: FAILED! => {"msg": "template error while templating string: Could not load \"ansible.utils.next_nth_usable\": \"cannot import name 'environmentfilter' from 'jinja2.filters' (/usr/lib/python3.9/site-packages/ansible/_vendor/jinja2/filters.py)\". String: {{ os_subnet_range | ansible.utils.next_nth_usable(10) }}. Could not load \"ansible.utils.next_nth_usable\": \"cannot import name 'environmentfilter' from 'jinja2.filters' (/usr/lib/python3.9/site-packages/ansible/_vendor/jinja2/filters.py)\""}

Any 4.15.z version

Always

    1. Get collections ansible-collection-ansible-netcommon and ansible-collection-community-general from OSP repo
    2. Run 4.15 UPI playbooks

The network.yaml playbook fails

Successful installation

https://github.com/openshift/installer/pull/8830 needs to be backported to 4.15. The automated cherry-pick to 4.15 failed so it requires manual intervention to fix the conflicts.
Otherwise the next replacements need to be done:
 - ansible.utils.next_nth_usable -> next_nth_usable
 - ansible.utils.ipaddr -> ipaddr