I ended up pushing a patch [1] for this as part of [2]. This has now
been released by upstream, so the change doesn't exist in the Guix
codebase any longer (the package was updated in [3]).
1: e61f092c877da5a9dc5dcdd82690bd3c191769e1
Duplicity fails to build, this might be because of the GPG version used,
as it looks to me that GPG complains that the message is quite old. I'll
ask on the Duplicity talk mailing list.
test_remove_all_inc_of_but_n (testing.functional.test_cleanup.CleanupTest) ...
ok
