Internal error "unexpected absent literal" with nurse.mzn

[metaleap]

MiniZinc IDE 2.8.0, default solver config & settings, happens with all built-in solvers, on a Linux 4.19 machine.

Here's the full nurse.mzn, identical to here except with the .dzn values inlined right into the code:

% Simple nurse rostering
include "regular.mzn";
enum NURSE = Nurse(1..7);
enum DAY = D(1..10);
int: req_day = 3;
int: req_night = 2;
int: min_night = 2;

enum SHIFT = { d, n, o };

enum STATE = { S1, S2, S3, S4, S5, S6 };

array[STATE,SHIFT] of opt STATE: t =
     [|      d:  n:  o:
      | S1:  S2, S3, S1
      | S2:  S4, S4, S1
      | S3:  S4, S5, S1
      | S4:  S6, S6, S1
      | S5:  S6, <>, S1
      | S6:  <>, <>, S1|];

array[NURSE,DAY] of var SHIFT: roster;

constraint forall(j in DAY)(
             sum(i in NURSE)(roster[i,j] == d) == req_day /\
             sum(i in NURSE)(roster[i,j] == n) == req_night
           );
constraint forall(i in NURSE)(
             regular([roster[i,j] | j in DAY], t, S1, STATE) /\
             sum(j in DAY)(roster[i,j] == n) >= min_night
           );

solve satisfy;

Output:

Command: minizinc --json-stream --param-file-no-push /tmp/mzn_AJTOTM.mpc /home/_/c/mz/mztut/2.3.5-nurse-rostering-orig.mzn
Configuration:
{
    "intermediate-solutions": true,
    "output-objective": true,
    "solver": "org.gecode.gecode@6.3.0"
}
MiniZinc has encountered an internal error. This is a bug.
Please file a bug report using the MiniZinc bug tracker.
The internal error message was: 
"unexpected absent literal"

[cyderize]

This is a duplicate of #752 and will be fixed in the next release. Thanks!