bpo-33358: Fix test_embed.test_pre_initialization_sys_options (GH-6612)


Fix test_embed.test_pre_initialization_sys_options() when building with --enable-shared
(cherry picked from commit 4114846265536344538ae44cb8ffd8ce2903faf7)

Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
diff --git a/Lib/test/test_embed.py b/Lib/test/test_embed.py
index f926301..c52cb99 100644
--- a/Lib/test/test_embed.py
+++ b/Lib/test/test_embed.py
@@ -208,7 +208,7 @@
         Checks that sys.warnoptions and sys._xoptions can be set before the
         runtime is initialized (otherwise they won't be effective).
         """
-        env = dict(PYTHONPATH=os.pathsep.join(sys.path))
+        env = dict(os.environ, PYTHONPATH=os.pathsep.join(sys.path))
         out, err = self.run_embedded_interpreter(
                         "pre_initialization_sys_options", env=env)
         expected_output = (