[3.13] pythongh-128636: Fix crash in PyREPL when os.environ is overwritten with an invalid value for macOS (pythonGH-138089)

(cherry picked from commit 8ef7735)

Co-authored-by: yihong <zouzou0208@gmail.com>
Signed-off-by: yihong0618 <zouzou0208@gmail.com>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Author: 3 people