I tried to save the page https://pt.wikipedia.org/w/index.php?title=Teste/123&action=edit with the content {{er}} to test one of our filters, and I got a warning message containing some raw HTML code:

<div class="mw-parser-output"><p>Página nova sem espaço </p></div>

This should no be escaped (and I'm sure it wasn't until some time ago).

For the record: these are the logs for the edit I tried to save:
https://pt.wikipedia.org/wiki/Special:AbuseLog?wpSearchUser=Reverta-me&wpSearchTitle=Teste%2F123