Issue #8533: regrtest replaces also sys.stdout on Windows

Replace sys.stdout to use backslashreplace. Use '\n' newline on all operating
systems.

Lib/test/regrtest.py

@@ -794,17 +794,14 @@ def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS):
 def replace_stdout():
     """Set stdout encoder error handler to backslashreplace (as stderr error
     handler) to avoid UnicodeEncodeError when printing a traceback"""
-    if os.name == "nt":
-        # Replace sys.stdout breaks the stdout newlines on Windows: issue #8533
-        return
-
     import atexit
 
     stdout = sys.stdout
     sys.stdout = open(stdout.fileno(), 'w',
         encoding=stdout.encoding,
         errors="backslashreplace",
-        closefd=False)
+        closefd=False,
+        newline='\n')
 
     def restore_stdout():
         sys.stdout.close()