Bug: `<template>` tag content rendered twice

[marvinhagemeister]

• Check if updating to the latest Preact version resolves the issue

Describe the bug
Template tag content is rendered twice. My guess is that the oldDom pointer is wrong somewhere when recursing into <template> tags.

EDIT: Looks like the actual dom is stuck in excessiveDomChildren

To Reproduce

it('should hydrate <template> tags ', () => {
  function App() {
    return <template><h1>it works</h1></template>
  }

  scratch.innerHTML = `<template><h1>it works</h1></template>`

  render(<App />, scratch);

  expect(scratch.innerHTML).to.equal(`<template><h1>it works</h1></template>`)
});

Expected behavior
No duplicate content.