Right. When the Ames CTO left to form Nebula and took soem personnel with him, that also removed advocates from within NASA: https://gigaom.com/2011/07/27/ex-nasa-cto-builds-cloud-dream...

But my understanding is that the European OpenNebula grew out of some of the same initial NASA Nebula code, and some folks went to the US subsidiary they created.

Now, while I was paying attention at the time, I didn't exactly have a front-row seat, and my memory could be wrong - three open source projects and three companies all with near identical names is a bit confusing!