The MIT license clearly states: "A short, permissive software license. Basically, you can do whatever you want as long as you include THE ORIGINAL COPYRIGHT and license notice in any copy of the software/source" (https://tldrlegal.com/license/mit-license).

This is how the original code looked: "// Copyright (c) 2009 Satoshi Nakamoto
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php."
(https://github.com/trottier/original-bitcoin/blob/92ee8d9a994391d148733da77e2bbc2f4acc43cd/src/script.cpp#L826).

And the Coreians' code changed the copyright so it has become null and void. This is how the copy right reads now: "The MIT License (MIT) Copyright (c) 2009-2019 The Bitcoin Core developersCopyright (c) 2009-2019 Bitcoin Developers" (https://github.com/bitcoin/bitcoin/blob/master/COPYING).