It's even more nuanced than that: the Squeak project took the time to actually do a full hunt for all of the old contributors, figured out who they were, rewrot

It's even more nuanced than that: the Squeak project took the time to actually do a full hunt for all of the old contributors, figured out who they were, rewrote their code when necessary, and got signed legal agreements authorizing the relicensing of their code under the MIT license. The Pharo project took a more practical but somewhat more cavalier approach without the lawyers and signatories. So there is actually the chance, though I want to emphasize very strongly a ridiculously tiny chance, that something in Pharo is incorrectly licensed at this point, whereas Squeak is legally unquestionably fully MIT licensed. That said, unless you wear a tinfoil hat, I cannot imagine anyone seriously not using Pharo due to the above.