From be7bd4be4fea94bd41253b71acb8aedb3833d7a8 Mon Sep 17 00:00:00 2001
From: Benedek Racz <betontalpfa@gmail.com>
Date: Mon, 30 Mar 2020 16:39:48 +0200
Subject: [PATCH] [FIX] PYTHONPATH grew run-to-run. Fix #31

---
 wexpect/host.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/wexpect/host.py b/wexpect/host.py
index b2c8336..9ac1b5e 100644
--- a/wexpect/host.py
+++ b/wexpect/host.py
@@ -351,7 +351,8 @@ class SpawnBase:
         console_args = f" {console_class_parameters_str} -- {args_str}"
 
         # set environment variables for the console
-        environ = os.environ
+        # Deep copy needed to prevent cycle-to-cycle growth. See #31 for more details.
+        environ = os.environ.copy()
 
         if getattr(sys, 'frozen', False):
             '''Runing in a PyInstaller bundle: