This blocks some of our new features, also plenty of people are running into this in the wild and getting exceptions.

Some things that need to happen here:

• swing app: the button on bottem left for nurse rostering 3 times (1
  unsolved, 1 solves, 1 solved again)
• benchmark with the stats that use constraint match
• FULL_ASSERT, NON_INTRUSIVE_FULL_ASSERT (maybe FAST_ASSERT), CH and 20
  secs LS on diverse of examples