Issue 15777: Fix a refleak in _posixsubprocess.
It was exposed by 03c98d05b140 and dbbf3ccf72e8.
R
Ross Lagerwall committed
f2b34b8b9669598d4294488cf3bb8ab4465b7097
Parent: 01d1837
It was exposed by 03c98d05b140 and dbbf3ccf72e8.