There appears to be some sort of bug affecting a subset of pages that started happening yesterday night. Certain <img src=> tags on Wikipedia's API are being served with an invalid URL, missing the scheme in front:
<img src="//bits.wikimedia.org/skins-1.17/common/images/magnify-clip.png">
This is seen on http://en.wikipedia.org/w/api.php?action=parse&page=Cereal
However certain other pages, such as http://en.wikipedia.org/w/api.php?action=parse&page=Actinide appear to be fine.
Please let me know if this e-mail should go to some Wikipedia list instead.
Thanks,
Robert