Hugo 0.18 with uglyURLs=TRUE adds an extra .html to variables such as .URL and .RelPermalink in list.html and terms.html.
template
<a href="{{ .URL }}">{{ .Title }}</a>
0.17 product
<a href="/tags/python.html">Python</a>
0.18 product
<a href="/tags/python.html.html">Python</a>
No _index.md for those pages exist yet. My current workaround is to use 0.17 or replace function.
Thanks.