Comment 4 for bug 2065120

The multi-value cloning bug can be reproduced more simply with this:

====
import bs4
import copy

html_doc = '<p class="foo"/>'
soup = bs4.BeautifulSoup(html_doc, "lxml")
p1 = soup.find("p")
p2 = p1._clone()
p1.attrs["class"].append("BAR") # <-- also affects p2

print(f"p1: {p1}")
print(f"p2: {p2}")
====