DConfChangeset: pointless fiddling with asserts
DConfChangeset: pointless fiddling with asserts

Adjust the way that an assert is done in order to convince lcov that we
have 100% line coverage (since the 'g_assert_not_reached()' wasn't being
hit before).

GNOME/dconf,GNOME/dconf,GNOME/dconf,GNOME/dconf