Don't touch PYTHONPATH if not set

Author: xrmx

opentelemetry-instrumentation/src/opentelemetry/instrumentation/auto_instrumentation/__init__.py

@@ -121,9 +121,10 @@ def run() -> None:
 def initialize():
     """Setup auto-instrumentation, called by the sitecustomize module"""
     # prevents auto-instrumentation of subprocesses if code execs another python process
-    environ["PYTHONPATH"] = _python_path_without_directory(
-        environ.get("PYTHONPATH", ""), dirname(abspath(__file__)), pathsep
-    )
+    if "PYTHONPATH" in environ:
+        environ["PYTHONPATH"] = _python_path_without_directory(
+            environ["PYTHONPATH"], dirname(abspath(__file__)), pathsep
+        )
 
     try:
         distro = _load_distro()

opentelemetry-instrumentation/tests/auto_instrumentation/test_initialize.py

@@ -30,7 +30,7 @@ class TestInitialize(TestCase):
     @patch("opentelemetry.instrumentation.auto_instrumentation._logger")
     def test_handles_pythonpath_not_set(self, logger_mock):
         auto_instrumentation.initialize()
-        self.assertEqual(environ["PYTHONPATH"], "")
+        self.assertNotIn("PYTHONPATH", environ)
         logger_mock.exception.assert_not_called()
 
     @patch.dict("os.environ", {"PYTHONPATH": "."})