There is a bug in the upgrade path from the old kmod-openvswitch SysV
based RPM to the new openvswitch-kmod systemd based RPM. Since the
name of the package is changed it is not possible to use the yum
or rpm upgrade options. This prevents passing in a 1 or 2 to the
%postun scriptlet section of the older RPM and that causes the section
to be treated as an 'erase'. The old kmod-openvswitch %postun section
proceeds to erase the symlinks in ../weak-updates/openvwswitch that
the installation of the new package had just created.
Fix this by adding a %posttrans tag to the systemd spec file. This
scriptlet is called after the symlinks have just been erased and
it calls the ovs-kmod-manage.sh script to recreate the symlinks and
run depmod -a again so that the correct kernel modules will be
found and loaded.