bpo-38991: Remove test.support.strip_python_stderr() (GH-17490)

test.support: run_python_until_end(), assert_python_ok() and
assert_python_failure() functions no longer strip whitespaces from
stderr.
diff --git a/Lib/test/test_gc.py b/Lib/test/test_gc.py
index fdb8752..c0d4a75 100644
--- a/Lib/test/test_gc.py
+++ b/Lib/test/test_gc.py
@@ -1,7 +1,7 @@
 import unittest
 import unittest.mock
 from test.support import (verbose, refcount_test, run_unittest,
-                          strip_python_stderr, cpython_only, start_threads,
+                          cpython_only, start_threads,
                           temp_dir, requires_type_collecting, TESTFN, unlink,
                           import_module)
 from test.support.script_helper import assert_python_ok, make_script
@@ -671,8 +671,8 @@
             p.stdout.close()
             p.stderr.close()
             self.assertEqual(p.returncode, 0)
-            self.assertEqual(stdout.strip(), b"")
-            return strip_python_stderr(stderr)
+            self.assertEqual(stdout, b"")
+            return stderr
 
         stderr = run_command(code % "0")
         self.assertIn(b"ResourceWarning: gc: 2 uncollectable objects at "