Recent change to link html code?

I’ve noticed recently that links are being added with different variations in the html code, eg

<a href="http://link"></a>
 <a href='http://link'></a>
 <a href="http://link" /></a>

Whereas usually it was simply <a href=”http://link”></a>. I’ve noticed in a lot of my WP-based engines that if a link is submitted with href=” (single quotes) rather than href=”” the link will not get posted correctly. I’ve had to add:

html to custom link format=1
 custom link format=<a href="%url%">%anchor_text%</a>
to my engines to fix this issue. I haven’t had a chance to do much testing with the default engines but am not sure whether it’s having an effect on them or not.