On Android setting Map.visibleRegion doesn't adjust map zoom when region is small

Consider the demo attached to `main.qml`. It creates a circle on a map, and then reduces its radius significantly and updates `visibleRegion` to match. It turns out that when the `radius` is small enough, the map zoom doesn't adjust, it stays the same (even if you pinch to zoom in/out and pan, the map recenters on subsequent `visibleRegions` assignments, but does not adjust zoom level).

The issue does not seem to present when using a "Desktop" kit.