Multiple self-closing tags are incorrectly parsed

[bigmeow]

Examples of errors

const Soup = require("soup");
soup = new Soup(`
<image src="123" />
<image src="abc" />
`);
soup.setAttribute("image[src]", "src", (url) => {
    return url + "?test";
});

console.log(soup.toString());

Expected output:

<image src="123?test" />
<image src="abc?test" />

Current output:

<image src="123?test" />
<image src="abc?testabcabc?test" />

Correct example

const Soup = require("soup");
soup = new Soup(`
<image src="123"></image>
<image src="abc"></image>
`);
soup.setAttribute("image[src]", "src", (url) => {
    return url + "?test";
});

console.log(soup.toString());

/*
<image src="123?test"></image>
<image src="abc?test"></image>
*/