[Merge] ~xnox/grub:fix-postinst into ~ubuntu-core-dev/grub/+git/ubuntu:focal-security

[Robert C Jennings]

Review: Needs Information

Dimitri, you've asked for my review and this addition looks reasonable, but I'm not familiar enough with the code to know if the next block dealing with install_devices_empty should still break during non-interactive or if it should be similarly changed.
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https://code.launchpad.net/~xnox/grub/+git/grub/+merge/388383
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~xnox/grub:fix-postinst into ~ubuntu-core-dev/grub/+git/ubuntu:focal-security.