Tags that are self-closing in HTML create unexpected results in XML

[acabal]

Consider this XML:

<?xml version="1.0" encoding="utf-8"?>
<package xmlns="http://www.idpf.org/2007/opf">
	<meta>Foobar</meta>
	<meta>Foo bar</meta>
</package>

Placing the cursor in the first <meta> element, then expanding the region, correctly selects Foobar, then <meta>Foobar</meta> as expected.

However, placing the cursor in the second <meta> element, then expanding the region, first selects Foo, then the entire document. The expected result is Foo, then Foo bar, then <meta>Foo bar</meta>.

I believe this is because ExpandRegion is treating this as HTML, in which <meta> is a self-closing tag; see expand_to_xml_node.py line 109. But it's not HTML, it's XML, and the rules are a little different.

Setting void_elements = [] solves this issue, but presumably creates undesired behavior when expanding in HTML and not XML.