Fixed #32094 -- Fixed flush() calls on management command self.stdout/err proxies.

tests/user_commands/management/commands/outputwrapper.py

@@ -0,0 +1,8 @@
+from django.core.management.base import BaseCommand
+
+
+class Command(BaseCommand):
+    def handle(self, **options):
+        self.stdout.write('Working...')
+        self.stdout.flush()
+        self.stdout.write('OK')