Inherit interpreter flags in parallel testing

Lib/test/support.py

@@ -1327,3 +1327,22 @@ def strip_python_stderr(stderr):
     """
     stderr = re.sub(br"\[\d+ refs\]\r?\n?$", b"", stderr).strip()
     return stderr
+
+def args_from_interpreter_flags():
+    """Return a list of command-line arguments reproducing the current
+    settings in sys.flags."""
+    flag_opt_map = {
+        'bytes_warning': 'b',
+        'dont_write_bytecode': 'B',
+        'ignore_environment': 'E',
+        'no_user_site': 's',
+        'no_site': 'S',
+        'optimize': 'O',
+        'verbose': 'v',
+    }
+    args = []
+    for flag, opt in flag_opt_map.items():
+        v = getattr(sys.flags, flag)
+        if v > 0:
+            args.append('-' + opt * v)
+    return args