Good catch! The technique needs modification to handle uncertainty (i.e. if we don't know which variation of the digit this clock uses), by relaxing the constra

Good catch! The technique needs modification to handle uncertainty (i.e. if we don't know which variation of the digit this clock uses), by relaxing the constraints around the uncertain LED segments for the digits with variations. My guess is that the problem will still be constrained enough to be easily solvable again by constraint propagation, but I haven't tested that.