This bug was fixed in the package grub2-signed - 1.66.12
--------------- grub2-signed (1.66.12) xenial; urgency=medium
* Rebuild against grub2 2.02~beta2-36ubuntu3.12. (LP: #1696599)
-- Mathieu Trudel-Lapierre <email address hidden> Wed, 14 Jun 2017 14:39:30 -0400
This bug was fixed in the package grub2-signed - 1.66.12
---------------
grub2-signed (1.66.12) xenial; urgency=medium
* Rebuild against grub2 2.02~beta2- 36ubuntu3. 12. (LP: #1696599)
-- Mathieu Trudel-Lapierre <email address hidden> Wed, 14 Jun 2017 14:39:30 -0400