If we had two deployments with different boot checksums, and were
trying to remove the one that was the same and add a new one (the
normal case), we'd end up assuming due to comparison with 0 that
we only needed to do the fast subbootversion swap.
Fix this by actually putting 1 where we really mean 1.
And update the tests to verify the fix; I have double-verified by
undoing the fix, and noting that the test fails.
https://bugzilla.gnome.org/show_bug.cgi?id=708351
298625d7f8