There are many people unaffiliated with the core Bitcoin developers who watch the git repo carefully, so such a heist would be impossible to pull off undetectably. Not to mention that the developers themselves form a geographically and politically diverse group (to the best of my knowledge none of them identify as thieves though
). You are welcome and encouraged to read the pull requests and commits. Every bit of oversight helps, even if you are not religious about it.
But of course, a third-party test suite would be a great thing to have. If you want to spearhead such a project I think that'd be a welcome contribution.
Now, having said that, what happened to Mt. Gox has nothing to do with anybody else's code, because Mt. Gox was running their own unpublished in-house code, and it was this code that had their fatal bugs.
