With preupgrade-assistant-el6toel7-0.7.3-0.201805031451Z.PR78.el6_8.noarch, this can be seen when upgrading on ppc64:
...
[ 9228.421009] upgrade-post[7660]: Running /root/preupgrade/postupgrade.d/grubby_workaround/postupgrade.sh...
[ 9228.463151] upgrade-post[7660]: ./postupgrade.sh: line 42: /boot/grub/grub.conf: No such file or directory
...
It should not be because grub.conf is not supposed to be consulted at all on ppc64.
With preupgrade-assistant-el6toel7-0.7.3-0.201805031451Z.PR78.el6_8.noarch, this can be seen when upgrading on ppc64:
It should not be because grub.conf is not supposed to be consulted at all on ppc64.