@julian but the point is that I haven't modified any of those files. Most of the files were text files like for example: README.md, LICENSE, etc.
Why would I modify any of those?
Tweaked settings in admin control panel
Tried to update to 0.7.3 -> got errors
Actually I got help from Nodebbs IRC- channel on how to resolve these errors with git and I'm now running 0.7.3. but it was not easy, I've no experience with git and no idea why I have to deal with stuff like this when updating.