Unset env variables in tests by del os.environ

The `unsetenv()` operation does not update `os.environ`.
https://docs.python.org/3/library/os.html#os.unsetenv

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/utils.py b/tests/utils.py
index eb2c40c52..329695c8e 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -62,4 +62,4 @@ def modify_env(**env):
             try:
                 os.environ[k] = original_env[k]
             except KeyError:
-                os.unsetenv(k)
+                del os.environ[k]