The value in the attribute displaytitle must contain valid HTML. The
sanitizer of the {{DISPLAYTITLE}} parser ensures that only valid HTML
is accepted.
If there is no {{DISPLAYTITLE}} in the wikitext then displaytitle
falls back to $title->getPrefixedText(). Here an HTML encoding of
special characters is necessary. This affects only the replacement of
& by & because other special characters like < and > are not
allowed in the title.
This change affects the displaytitle fallback on the following places:
* ApiParse
* ApiQueryInfo
* InfoAction
* Parser
The displaytitle fallback in OutputPage is also updated to this
behavior although
Sanitizer::normalizeCharReferences( Sanitizer::removeHTMLtags( $html )
also replaces & by &.
Also add test cases with & in the displaytitle to:
* ApiParseTest
* ApiQueryInfoTest
* parserTests
Bug: T291985
Change-Id: I8ee1e2731d9bfa49725d663b34986e7e3073e4ca
eed3121a8f