- Issue #13703: oCERT-2011-003: add -R command-line option and PYTHONHASHSEED

environment variable, to provide an opt-in way to protect against denial of
  service attacks due to hash collisions within the dict and set types.  Patch
  by David Malcolm, based on work by Victor Stinner.

Lib/test/test_support.py

@@ -24,7 +24,7 @@ __all__ = ["Error", "TestFailed", "TestSkipped", "ResourceDenied", "import_modul
            "captured_stdout", "TransientResource", "transient_internet",
            "run_with_locale", "set_memlimit", "bigmemtest", "bigaddrspacetest",
            "BasicTestRunner", "run_unittest", "run_doctest", "threading_setup",
-           "threading_cleanup", "reap_children"]
+           "threading_cleanup", "reap_children", "strip_python_stderr"]
 
 class Error(Exception):
     """Base class for regression test exceptions."""
@@ -893,3 +893,13 @@ def reap_children():
                     break
             except:
                 break
+
+def strip_python_stderr(stderr):
+    """Strip the stderr of a Python process from potential debug output
+    emitted by the interpreter.
+
+    This will typically be run on the result of the communicate() method
+    of a subprocess.Popen object.
+    """
+    stderr = re.sub(br"\[\d+ refs\]\r?\n?$", b"", stderr).strip()
+    return stderr