Debug branch: Soundness bug in QF_NIA formula with smt.random_seed 6

[wintered]

The following trace shows a soundness bug in z3debug. Setting the random seed to 6 is necessary to trigger the bug.

[759] % z3 bug.smt2 
sat
[760] % z3debug bug.smt2 
unsat
[761] % 
[761] % cat bug.smt2 
(set-option :smt.random_seed 6)
(declare-fun x () Int)
(assert (= (mod (+ 130 x) 100) (mod (- 2 (* 7839 x)) 132)))
(check-sat)

OS: Ubuntu 18.04
Commit: 8d39694

[NikolajBjorner]

fixed df76970