[CentOS] CentOS 7 1708 won't boot after grub2 update

Hi all,

This is the third fresh install of CentOS 7 1708 the last two months that
won't boot after a regular "yum update" just after the fresh install has
finished.

I've never had this problem before, it has just worked. 
The installs are on OEM's that have previously run CentOS 6.9 x64.

Am I missing something here?

-- 
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