I think you need to learn more about open source, it's pure transparency, how can a project be open source and still have a backdoor? And no one sees the back door? What's the open source then?
Open-source projects have nothing to hide, you can easily see all their codes and what they are running, with no hide-and-seek like Closed source, what you just defined sounds exactly like Closed source projects.
That's mostly true, but knowing how complex code can be depending on the project, the developer can easily have an obfuscated backdoor in the source code. It'll take a very competitive developer or a developer that's specifically looking for such an exploit/backdoor to spot it.
2017: "backward compatibility", no longer requires consensus upgrade first to vote in an activation. its now a 'just let the horse in, its fine we dont need to check it, we trust someone else has before'
just saying.. there is a back door. but seems no one cares that consensus is not the same byzantine generals solution of 2009-2014