At the end of the credits there is a quote from Mark Twain ("Twenty years from now you will be more disappointed by the things that you didn't do ..." etc.).
I remember a few versions ago / when the end was implemented it said "- Mark Twain" like here, but now it's just "- Unknown".
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As of 1.3.2 the quote credit has been changed deliberately from Mark Twain to Unknown, so this is not a bug.