test_doctest fails since r59984.

Not sure if these are the correct values, but save_stdout has to be set before its usage...

Lib/pdb.py

@@ -199,6 +199,8 @@ def default(self, line):
         globals = self.curframe.f_globals
         try:
             code = compile(line + '\n', '<stdin>', 'single')
+            save_stdout = sys.stdout
+            save_stdin = sys.stdin
             try:
                 sys.stdin = self.stdin
                 sys.stdout = self.stdout