The Bot Project is all about the webmaster community working together to build a picture of what search engine bots are doing, when they're doing it and where they're from.

Will this code have any impact on my ranking?

No. The search engines won't be aware that your robots.txt is being tracked so if, for some bizarre reason, they all decided that the bot project was dangerous to them and wanted to penalise everyone involved (think paid-for links), they simply couldn't... unless they just penalised everyone which would kinda level things out again...