Refs #25838 -- Removed the deprecated shell --plain option.

django/core/management/commands/shell.py

 import os
 import select
 import sys
-import warnings
 
 from django.core.management import BaseCommand, CommandError
 from django.utils.datastructures import OrderedSet
-from django.utils.deprecation import RemovedInDjango20Warning
 
 
 class Command(BaseCommand):
@@ -19,11 +17,6 @@ class Command(BaseCommand):
     shells = ['ipython', 'bpython', 'python']
 
     def add_arguments(self, parser):
-        parser.add_argument(
-            '--plain', action='store_true', dest='plain',
-            help='Tells Django to use plain Python, not IPython or bpython. '
-                 'Deprecated, use the `-i python` or `--interface python` option instead.',
-        )
         parser.add_argument(
             '--no-startup', action='store_true', dest='no_startup',
             help='When using plain Python, ignore the PYTHONSTARTUP environment variable and ~/.pythonrc.py script.',
@@ -83,13 +76,6 @@ class Command(BaseCommand):
         code.interact(local=imported_objects)
 
     def handle(self, **options):
-        if options['plain']:
-            warnings.warn(
-                "The --plain option is deprecated in favor of the -i python or --interface python option.",
-                RemovedInDjango20Warning
-            )
-            options['interface'] = 'python'
-
         # Execute the command and exit.
         if options['command']:
             exec(options['command'])

docs/ref/django-admin.txt

@@ -951,11 +951,6 @@ Python interpreter, use ``python`` as the interface name, like so::
 
     django-admin shell -i python
 
-.. deprecated:: 1.10
-
-   In older versions, use the ``--plain`` option instead of ``-i python``. This
-   is deprecated and will be removed in Django 2.0.
-
 .. _IPython: https://ipython.org/
 .. _bpython: http://bpython-interpreter.org/
 

docs/releases/2.0.txt

@@ -338,3 +338,5 @@ these features.
   is removed.
 
 * ``django.utils.functional.allow_lazy()`` is removed.
+
+* The ``shell --plain`` option is removed.