Comment 7 for bug 1641931

@ologvinova
there is 3 workarounds:
1 - update to 9.1 right after fuel installation
2 - disable mos9.0-updates repository at "fuelmenu" step by direct ssh to node and "yum-config-manager --disable mos9.0-updates --save"
3 - downgrade 4 packages and re-run migration script

the first and the second was already verified, we only need to find proper set of commands for the third one. Will try to do this (or @vryzhenkin can help with it)