Fix IUK generation in release process
Originally created by @intrigeri on #17415 (Redmine)
(19:26:02) kibi: intrigeri: the loop is still buggy
(19:26:13) kibi: also, it happily ignores failures and continues
(19:26:21) kibi: chown: cannot access '"/home/kibi/work/clients/tails/release/isos/iuks/v2/Tails_amd64_4.0_to_4.2.1.iuk"': No such file or directory
(19:29:54) kibi: I don't plan on fixing shell quoting issues (meaning testing the bugfixes) on my own
(19:30:09) kibi: at least not right now; and I don't think I need you to do it instead, now.
(19:30:35) kibi: maybe file a ticket? I might take a little break while the IUKs are grinding.
Feature Branch: doc/17415-fix-IUK-generation-in-release-process