From ac20cd1dd3e8c5aafdfc1dad48335511e63e73eb Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Tue, 16 May 2023 13:42:53 +0200
Subject: [PATCH] Tolerate urllib3.response.HTTPResponse.msg being None

---
 vcr/stubs/__init__.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/vcr/stubs/__init__.py b/vcr/stubs/__init__.py
index 5f7fac7..c1c4654 100644
--- a/vcr/stubs/__init__.py
+++ b/vcr/stubs/__init__.py
@@ -47,8 +47,9 @@ def parse_headers(header_list):
 
 
 def serialize_headers(response):
+    headers = response.headers if response.msg is None else response.msg
     out = {}
-    for key, values in compat.get_headers(response.msg):
+    for key, values in compat.get_headers(headers):
         out.setdefault(key, [])
         out[key].extend(values)
     return out