bpo-31904: fix test_doctest.py failures for VxWorks (GH-23419)

Fix test_doctest.py failures for VxWorks by avoiding exact error message checks. (better for everyone all around)

Author: pxinwr

Lib/test/test_doctest.py

@@ -3039,10 +3039,11 @@ def test_CLI(): r"""
     ...         '-m', 'doctest', 'nosuchfile')
     >>> rc, out
     (1, b'')
+    >>> # The exact error message changes depending on the platform.
     >>> print(normalize(err))                    # doctest: +ELLIPSIS
     Traceback (most recent call last):
       ...
-    FileNotFoundError: [Errno ...] No such file or directory: 'nosuchfile'
+    FileNotFoundError: [Errno ...] ...nosuchfile...
 
 Invalid doctest option:
 

Misc/NEWS.d/next/Tests/2020-11-20-15-07-18.bpo-31904.EBJXjJ.rst

@@ -0,0 +1 @@
+Fix test_doctest.py failures for VxWorks.