Restrict libvirt-python 4.1.0
Restrict libvirt-python 4.1.0

This version contains bug that prevents its installation
https://bugs.launchpad.net/openstack-requirements/+bug/1753539

Change-Id: I8d0fd2bac7217192362215c0cc33b9be673911a7

stackforge/fuel-devops,stackforge/fuel-devops