While installing ovirt-provider-ovn, python-openvswitch >= 2.6 is required to complete the transaction.

This works fine when you try to install manually (yum install ..), the dependencies are resolved correctly.
The problem is with automated install using python-dnf, like for example during engine-setup. It looks like this is not handled correctly there.
The error message:
[ ERROR ] Failed to execute stage 'Environment customization': package ovirt-provider-ovn-1.1-2.20170406112359.git8dedb67.fc25.noarch requires python-openvswitch >= 2.6, but none of the providers can be installed
log:
2017-04-10 11:19:54 DEBUG otopi.context context._executeMethod:142 method exception
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/otopi/context.py", line 132, in _executeMethod
    method['method']()
  File "/usr/share/ovirt-engine/setup/bin/../plugins/ovirt-engine-setup/ovirt-engine-common/distro-rpm/packages.py", line 360, in _customization
    ) = self._checkForProductUpdate()
  File "/usr/share/ovirt-engine/setup/bin/../plugins/ovirt-engine-setup/ovirt-engine-common/distro-rpm/packages.py", line 245, in _checkForProductUpdate
    if mpm.buildTransaction():
  File "/usr/lib/python2.7/site-packages/otopi/minidnf.py", line 609, in buildTransaction
    ret = self._base.resolve(allow_erasing=True)
  File "/usr/lib/python2.7/site-packages/dnf/base.py", line 541, in resolve
    raise exc
DepsolveError: package ovirt-provider-ovn-1.1-2.20170406112359.git8dedb67.fc25.noarch requires python-openvswitch >= 2.6, but none of the providers can be installed


Checked python-openvswitch:
rpm -q --provides python2-openvswitch
 python-openvswitch = 2.7.0-1.fc25
 python2-openvswitch = 2.7.0-1.fc25

So the issue is that minidnf is not able to resolve the provided python-openvswitch = 2.7.0-1.fc25 while dnf succeed.