What's the best way to test mainline Ubuntu without destroying my Kubuntu install?

[Ralf Mardorf]

On Thu, 18 Apr 2019 11:26:25 +0200, Ralf Mardorf wrote:
>On Wed, 17 Apr 2019 22:00:45 +0100, Colin Law wrote:
>>On Wed, 17 Apr 2019 at 17:30, Christopher Patti <feoh at feoh.org>
>>wrote:  
>>> Pardon the stupid question but will that overwrite my current GRUB
>>> configuration or simply add a new entry to boot Ubuntu/Gnome?    
>>
>>Not stupid at all.  It will add a new one to the boot list.  The
>>default will be the new one and the original will be an option.  To
>>put the default back to the original (with the new one an option) boot
>>into the original and run
>>sudo grub-install /dev/sda   # assuming that sda is the boot drive
>>sudo update-grub

Oops, ok, the above describes the required manual intervention :D. 

>AFAIK it will not add anything to the grub config of the original
>install. AFAIK grub is taken over by the new Ubuntu (flavour) install.
>It most likely is possible to chose the original or the new install by
>default, but assuming the OP should decide to remove the new install,
>there's the need to manually fix grub after removing the new install.