Last modified: 2012-12-18 23:08:22 UTC
Probably some issue with an image magick upgrade. File's are supposed to have a comment (in JPEG's have a COM segment) that has a url to the file's source. Recently created thumbnails appear to lack this. See for example: http://regex.info/exif.cgi?dummy=on&imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2Fb%2Fbf%2FSBB_Webkartenportal_iPad.jpg%2F800px-SBB_Webkartenportal_iPad.jpg which doesn't list a COM segment on the thumb. PNG thumbs are also lacking such a comment. See also bug 18871
For completeness, here is the expected metadata (from what is presumably an older cached thumb): http://regex.info/exif.cgi?dummy=on&imgurl=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F3%2F3a%2FCommon_Mime_Papilio_clytia_Form_clytia_by_kadavoor.jpg%2F800px-Common_Mime_Papilio_clytia_Form_clytia_by_kadavoor.jpg
Testing locally, the comment still gets added. Additionally no one has touched the relavent code on the MediaWiki side for about 2 years. Hence all signs point to something on the wmf server end. Adding keyword ops
