jessor/zeitgeist — comment on commit a76e9cab6b75e1b4578f9b9199eb13b7852c3bce
File:  line 0
By 4poc:

image magick in the version used on the server is writing the mtime stamp into png files after stripping metadata, rendering the md5 dupecheck that are preformed after this, void:
wget http://cheezfailbooking.files.wordpress.com/2012/02/funny-facebook-fails-donggy.png -O test.png; md5sum test.png; convert test.png -strip stripped1.png; md5sum stripped1.png; sleep 4; touch test.png; convert test.png -strip stripped2.png; md5sum stripped2.png