https://github.com/python/cpython/pull/7967 amends the docs and adds the deprecation notices, but after taking another look at the way Victor's patch works, I'm thinking we may not need them: the *new* initialization API remains strict about the required state machine transitions, which means that calling `Py_Initialize` when only the core has been initialized will fail at the _Py_InitializeCore step (as that complains if the core has already been initialized).

Similarly, calling _Py_InitializeCore after Py_Initialize still fails, as the *only* case that becomes a no-op is specifically Py_InitializeEx, *after* the interpreter is fully initialized.

Given that, I think we can just keep Victor's compatibility fix indefinitely, and only have the new incremental initialization APIs be strict about the expected transitions through the state machine.