The API docs as of 1.5 say that withDataAndEvents and deepWithDataAndEvents both default to false. However, they're both defaulting to true (lines 5139 and 5140):

dataAndEvents = dataAndEvents == null ? true : dataAndEvents;

deepDataAndEvents = deepDataAndEvents == null ? dataAndEvents :

If you call .clone() in 1.5 with no arguments, dataAndEvents is undefined, and undefined == null evaluates to true, so the default value winds up being true.

Not sure what the intent is, so I can't say if this is a typo in the docs are or of the code should change, but it seems like one of them should.