The CurveRenderer is leaking SGNodes when the renderer is deleted.

To reproduce one can run the manual test painterPathQuickShape. Changing the shape or changing the renderer will lead to leaked nodes. To get informed about leaking nodes run the test with QT_LOGGING_RULES qt*=false;qt.scenegraph.leaks=true.

The result will be something similar to:
qt.scenegraph.leaks: Number of leaked textures: 0
Number of leaked materials: 9
Number of leaked nodes: 9
Number of leaked pixmaps: 0

It does not always happen, so it might be the result of a racing condition.