Another splinter issue from issue13349. Currently, Element reports it's a list when remove is called on it:

    from xml.etree.ElementTree import Element
    Element('').remove(Element('')) 

    ValueError: list.remove(x): x not in list

From what I understand, this was done in order for it to conform with the error reporting performed from the pure python implementation of Element. (side note: These also differ regarding the type of value supplied to .remove, the C implementation only wants instances of Element)

The message, imo, is confusing and should be changed to Element.remove(x): x not in Element.