How to randomly rotate an ImageView with Kotlin

I'm trying to randomize the rotation of a circular imageview where the onAnimationRepeat should generate a new rotationEnd value and assume the rotationStart at the position where the last cycle has stopped - this is the code:

    var rotStart : Float = 0f
    var rotEnd : Float = randomNumberGenerator()
    val rand = Random()

    var rotateAnimation = RotateAnimation(
            rotStart, rotEnd,
            Animation.RELATIVE_TO_SELF, 0.5f,
            Animation.RELATIVE_TO_SELF, 0.5f

    )
    rotateAnimation.duration = 3000
    rotateAnimation.repeatCount = 20
    rotateAnimation.setAnimationListener(object : Animation.AnimationListener {

        override fun onAnimationStart(animation: Animation?) {
        }

        override fun onAnimationRepeat(animation: Animation?) {
            rotStart =  rotEnd
            rotEnd = rand.nextInt(359).toFloat()
            rotateAnimation = RotateAnimation(rotStart,rotEnd,
                    Animation.RELATIVE_TO_SELF, 0.5f,
                    Animation.RELATIVE_TO_SELF, 0.5f)

        }

        override fun onAnimationEnd(animation: Animation?) {


        }
    })

    img_spinner.startAnimation(rotateAnimation)
}

fun randomNumberGenerator(): Float {
    val rangeMin = 0f
    val rangeMax = 359f
    val r = Random()
    return rangeMin + (rangeMax - rangeMin) * r.nextFloat()
}

onAnimationRepeat should start with the value of the rotation-angle the image has experienced on the last cycle. With this code the rotation starts always with the value of: 0f and ends at the fixed value of "rotEnd" which the randomNumberGenerator() generated on the first run, so for example: 0 and 122 is generated on the first run, the image keeps spinning from 0 to 122 and ignores completely my code which I've written onAnimationRepeat.