If you add some data to a pie chart and then reload the view, the colors will change.

To check that it's bug, I wrote a simple test case with a pie chart that had only one data.

If you remove the data and add it again, the default color will change (css default color class is increased).

The expected default color should be default-color0 for the first data, even if we remove and add it again (by keeping only one data).