$ cat small.smt2
(declare-fun var810 () String)
(assert (and (forall ((va String)) (or (= "B" var810) (not (str.in_re va (re.union (str.to_re "z") (str.to_re (str.substr "z" 0 (str.len var810))))))))))
(check-sat-using ctx-solver-simplify)
$ z3 small.smt2
ASSERTION VIOLATION
File: ../src/smt/tactic/ctx_solver_simplify_tactic.cpp
Line: 140
UNEXPECTED CODE WAS REACHED.
(C)ontinue, (A)bort, (S)top, (T)hrow exception, Invoke (G)DB
a