How to restore the MBR after do-release-upgrade?

[Ralf Mardorf]

On Fri, 8 Jul 2016 21:18:18 +0200, Ralf Mardorf wrote:
>On Fri, 8 Jul 2016 14:59:40 +0200, Liam Proven wrote:
>>> What ever bootloader I use, how can I prevent the Ubuntu install
>>> from overwriting an existing bootloader next time I run
>>> do-release-upgrade?    
>>
>>If it's in *that installation's own root filesystem* then that is
>>where it should stay.  
>
>Thank you for the pointer.
>
>The do-release-upgrade only offers /dev/sda and /dev/sdb.

Maybe I'm mistaken, perhaps there was the option to select a partition
and I didn't select it, because I thought that I could restore
everything by the MBR backup.