Downgrade are failing because of python2-kubernetes version change

[alexandre-allard]

Component: salt

What happened: python2-kubernetes has been bump recently in epel repository, this version drops support of some apiVersion like V1beta1Ingress which we use, so we've replaced it with the new one ExtensionsV1beta1Ingress.
Problem is when we downgrade, we try to do some stuff using the downgraded salt-master container, with the current modules which contain the fix and it breaks.

[ERROR   ] Failed to import utils kubernetes_utils, this is due most likely to a syntax error:
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/salt/loader.py", line 1534, in _load_module
    mod = imp.load_module(mod_namespace, fn_, fpath, desc)
  File "/var/cache/salt/master/extmods/utils/kubernetes_utils.py", line 286, in <module>
    model=k8s_client.ExtensionsV1beta1Ingress,
AttributeError: 'module' object has no attribute 'ExtensionsV1beta1Ingress'

What was expected: Downgrade are working fine.

Steps to reproduce: Build an iso from the latest development/2.5, install it and try to downgrade to a 2.4.x released version.

Resolution proposal (optional):

[TeddyAndrieux]

Fixed by #2101