Without this, modifications to env propagate to unexpected places. This mirrors behaviour in Executable (where the code was copied from). Change-Id: I35bbf2f3cc2786eb50ff751c813853971ab284fe Signed-off-by: Nicolas Boichat <drinkcat@google.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/67233 Maintainer: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Jason Lowe-Power <power.jg@gmail.com> Reviewed-by: Gabe Black <gabe.black@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>