"Upgrade from ISO" fails from 32-bit Tails with 64-bit ISO

Originally created by @intrigeri on #11873 (Redmine)

Feature Branch: bug/11873+upgrade_32-bit_to_64-bit_ISO

Edited May 15, 2020 by intrigeri

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information