Angular.merge is not a function shows in angularjs chart integration

Question

I am using angularjs chartjs. There is no problem. But when I am using chart-dataset-override="datasetOverride" it shows the problem that angular.merge is not a function. I am using angularjs version 1.3.3. I have no option to upgrade angularjs now.

  <canvas id="pie" class="chart chart-line"
       chart-data="data" chart-labels="labels" chart-options="options" chart-dataset-override="datasetOverride">
    </canvas>