Newton's third law.

For the force the magnet exerts on the metal, there must be an equal an opposite force on the magnet exerted by the metal. Since both form one system (metal + truck + magnet), the net force on the system is zero, and it won't move.

Please explain the flaw in this picture
I created a fork of a public repository on BitBucket, with the sole purpose of committing a pull request that fixed some bug. The pull request was accepted and merged. Now, I want to delete the repository, that has outlived its purpose. If I do that, will the changes be lost?

There is already a question about this same issue, but for GitHub. Apparently, on GitHub you can delete the repository before the request has been even merged, as it gets automatically saved in the target repository. I guess that on BitBucket, things will be similar, but I wanted to be sure.
