gh-121571: Do not use `EnvironmentError` in tests, use `OSError` instead (#121572)

Lib/test/support/__init__.py

@@ -387,7 +387,7 @@ def skip_if_buildbot(reason=None):
         reason = 'not suitable for buildbots'
     try:
         isbuildbot = getpass.getuser().lower() == 'buildbot'
-    except (KeyError, EnvironmentError) as err:
+    except (KeyError, OSError) as err:
         warnings.warn(f'getpass.getuser() failed {err}.', RuntimeWarning)
         isbuildbot = False
     return unittest.skipIf(isbuildbot, reason)

Lib/test/test_subprocess.py

@@ -1407,7 +1407,7 @@ class ProcessTestCase(BaseTestCase):
         t = threading.Thread(target=open_fds)
         t.start()
         try:
-            with self.assertRaises(EnvironmentError):
+            with self.assertRaises(OSError):
                 subprocess.Popen(NONEXISTING_CMD,
                                  stdin=subprocess.PIPE,
                                  stdout=subprocess.PIPE,