Use the --timeout flag to change the timeout.
herbie shell --seed 2020273
(FPCore (alpha beta i)
:name "Octave 3.8, jcobi/2"
:precision binary64
:pre (and (> alpha -1.0) (> beta -1.0) (> i 0.0))
(/ (+ (/ (/ (* (+ alpha beta) (- beta alpha)) (+ (+ alpha beta) (* 2.0 i))) (+ (+ (+ alpha beta) (* 2.0 i)) 2.0)) 1.0) 2.0))