Incorrect sat answer on unsat Real formula

[muchang]

Hi,
For this formula:

(set-logic NRA)
(assert
    (forall
      ((b Real))
      (exists
        ((c Real))
        (and
          (< c 4)
          (not (= c (- 2)))
          (not (= c 0))
          (or
            (and
              (not
                (= (+ (* 8 b) (* 5 c)) 8)
              )
              (<
                (+ (* (- 80) b) (* (- 6) c))
                5
              )
            )
            (and
              (< (* (- 3) b) 1)
              (>= b 8)
            )
        )
      )
    )
  )
)
(check-sat)

latest Z3 reports sat on this unsat formula, while z3-4.8.5-stable reports unsat.

OS: Ubuntu 18.04
Revision: 6384080