In Ext JS 5.0.2.1397, it seems some of the api is not browser compatible with IE9.

I get Object doesn't support property or method 'setLineDash'.

Sprite.js?_dc=1412353940372, line 648 character 13

That was working in previous build.

Extract:

Code:
  /**
     * Applies sprite's attributes to the given context.
     * @param {Object} ctx Context to apply sprite's attributes to.
     * @param {Array} rect The rect of the context to be affected by gradients.
     */
    useAttributes: function (ctx, rect) {
        this.applyTransformations();
        var attrs = this.attr,
            canvasAttributes = attrs.canvasAttributes,
            strokeStyle = canvasAttributes.strokeStyle,
            fillStyle = canvasAttributes.fillStyle,
            lineDash = canvasAttributes.lineDash,
            lineDashOffset = canvasAttributes.lineDashOffset,
            id;


        if (strokeStyle) {
            if (strokeStyle.isGradient) {
                ctx.strokeStyle = 'black';
                ctx.strokeGradient = strokeStyle;
            } else {
                ctx.strokeGradient = false;
            }
        }


        if (fillStyle) {
            if (fillStyle.isGradient) {
                ctx.fillStyle = 'black';
                ctx.fillGradient = fillStyle;
            } else {
                ctx.fillGradient = false;
            }
        }


        if (lineDash) {
            ctx.setLineDash(lineDash);
        }
This is the diff, old code, versus new code in nightly build:
setLineDash.PNG
I have doubt on your nightly build setup. Is it always providing a zip even if it fail? Do you have any tests running?