What's the deal with http://dconf.org/2015/talks/zvibel.pdf?

[Andrei Alexandrescu via Digitalmars-d]

So this is the sixth time or so I change permissions for 
http://dconf.org/2015/talks/zvibel.pdf manually. I make it 
world-readable, someone within a matter of hours it becomes 
world-unreadable.

Attributes and owner are fine on my github dir. We use rsync.
Does any other contributor update dconf.org and has the wrong 
attributes? Could there be something more odd at work?


Andrei