Comment 10 for bug 1768330

more info:

this also affects .prettify()

e.g.

>>> markup = r'<p>lorem <a href="#">ipsum</a> dolor <span>sit</span> amet</p>'
>>> soup = BeautifulSoup(markup, 'html.parser')
>>> print(soup.prettify())
<p>
 lorem
 <a href="#">
  ipsum
 </a>
 dolor
 <span>
  sit
 </span>
 amet
</p>

both <a> and <span> are split into their own lines