Never send the DeviceChanged signal with old data
Never send the DeviceChanged signal with old data

If we connect up the device for property changes and then do an update,
we might send the pre-update GVariant data rather than the post-install
FuDevice.

This could mean that any client using the signal to update UI elements
might either flicker between the values, or show the 'wrong' device
version.

fwupd/fwupd,fwupd/fwupd,fwupd/fwupd,fwupd/fwupd