Assign selection to background via script

I do not see a way to assign the current selection (or the entire contents) of a given layer to its background layer. Is this possible?

thisLayer.setBackground_(thisLayer)

or

thisLayer.background.paths = [x.copy() for x in thisLayer.paths] # you need to copy the node, too.

And so on for all things you like to put in the background.

Or what I like to do:

thisLayer.setBackground_( thisLayer.copyDecomposedLayer() )

… to have reference layer of what the glyph originally looked like.