It appears the 787 was taxiing along minding its own business when a 380 reverses into him.
Or the ground crew pushed the A380 back, stopped for a few minutes and the other aircraft taxied into it.
I think the jury is still out on this one.
It could have been ATC's fault for giving clearance to push. If that diagram is to scale, it seems you can't push an aircraft from this gate without hanging an A380 wing over the taxiway. I don't see how you could push the aircraft in an arc to the centerline without reaching the next gate (C23).
http://www.fly-tea.com/cms/lib/skins...rport/WSSS.jpg