In commit b76c1846bbfd ("Settings update: Simplify Update Manager")
the logic for when to show the UpdateManger question to the user got
broken. Unintuitively, a boolean setting actually has three possible
values. True, False, and Unset. This patch fixes things to work as
designed again.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>