vm: with statement ignores a true non-bool __exit__ result #267

An __exit__ that returns a true value other than True does not silence the exception:

class Quiet:
    def __enter__(self):
        return self
    def __exit__(self, *exc):
        return 1

with Quiet():
    raise ValueError("boom")

print("ok")

On main (444ae5e):

ValueError: 'boom'

CPython prints ok: its WITH_CLEANUP tests the result with PyObject_IsTrue, while gpython's (vm/eval.go) compares it with py.True.

Go 1.27.1, darwin/arm64.