This is a parsing bug of MediaWiki on this wiki; this won't occur with a regular HTML parser. As I said, plain HTML links are not supported by Mediawiki as Mediawiki incorrectly includes the "trailing" quote in it. That's something that MediaWiki should fix as these quotes in HTML are never taken into account, unless they are URL-encoded in HTML.
Note that in HTML both the single quote and the double quotes are valid delimiters for attributes, and which ones are valid as part of the quoted value depends on which delimiting paired quotes are used:
- If attribute values are between double quotes
"...", litteral single quotes
'in the embedded value don't need to be encoded, but double quotes in attribute values have to be HTML-escaped as
"(or only if the value is an URL, they can be URL-encoded as
%22, which won't need any HTML-escapes)
- If attribute values are between single quotes
'...', litteral double quotes
"in the embedded value don't need to be encoded, but single quotes in attribute values have to be HTML-escaped as
'(or only if the value is an URL, they can be URL-encoded as
%27, which won't need any HTML-escapes)
Note that any single quote or double quotes by IS valid in any standalone URL (except for the leading protocol part or the host/domain part, it is valid anywhere in the optional parts: the path, the query string, fragment identifier) or any URI. Inside a standalone URI, there's no support at all for the HTML-encoding, or for the URL-encoding (which depends on the protocol and the target host/domain part in its own URL parser, but noit at all of the HTML-parser!!!).
Here MediaWiki (on this wiki) does not parse the HTML completely correctly and so it does not use the correct HTML-parsing for delimiting attributes, and then it considers the value as if it was between double quotes (no check is made about which effective delimtier is used in the HTML attribute, so it incorrectly accepts the single quote as part of it, then it takes the wrong decision).
This is effectively a bug of MediaWiki (which could be reported given that the MediaWiki should still parse HTML correctly and should be an extension of it), in its own custom parser. But as I said, this message is *not* to be parsed by MediaWiki and will be parsed by a regular HTML parser which makes the correct decision. The bug is bisible on this wiki when viewing the translated page, but it does not affect the application.