Users who are more familiar with XML than with HTML often write things like
<div style="clear:left;" />
The parser (function removeHTMLtags in Sanitizer.php) currently does this:
- If wgUseTidy is true, the pseudo-self-closed tag is left as is, and fixed by Tidy to <div style="clear:left;"></div> (or not, bug 38273)
- If wgUseTidy is false, the tag is flagged as "bad" and escaped to <div style="clear:left;" />
This is inconsistent, and makes it difficult to import text from a wiki with Tidy into a wiki without.
So self-closed tags that should be in pairs should be closed automatically by the parser. The current behavior was introduced as fix for bug 5487.