Set match_aspect on geographic Bokeh plots in datashader examples

As far as I can tell the aspect ratio in the example for census+hv+dask is not preserved when I select region of interest using Zoom Selection tool.
Mouse scrolling zoom works fine - but it updates every time I scroll which makes me wait for the final image to catch up with the final scroll.
So Zoom Selection should help to zoom once and to the place of interest.
Thanks!