[2.0.x] Fixed #28594 -- Removed Jython docs and specific code

Thanks Andrey Martyanov for the report, and Tim Graham for the review.
Backport of 23b21db31bfcf2a065d485617412cca43a311a4c from master.

8 files changed, 13 insertions, 119 deletions

diff --git a/django/core/management/templates.py b/django/core/management/templates.py
index eb4baafd62..a89a54fa62 100644
--- a/django/core/management/templates.py
+++ b/django/core/management/templates.py
@@ -5,7 +5,6 @@ import posixpath
 import re
 import shutil
 import stat
-import sys
 import tempfile
 from importlib import import_module
 from os import path
@@ -335,9 +334,6 @@ class TemplateCommand(BaseCommand):
         Make sure that the file is writeable.
         Useful if our source is read-only.
         """
-        if sys.platform.startswith('java'):
-            # On Jython there is no os.access()
-            return
         if not os.access(filename, os.W_OK):
             st = os.stat(filename)
             new_permissions = stat.S_IMODE(st.st_mode) | stat.S_IWUSR
diff --git a/django/utils/autoreload.py b/django/utils/autoreload.py
index 0081b502fe..534fb4af46 100644
--- a/django/utils/autoreload.py
+++ b/django/utils/autoreload.py
@@ -307,24 +307,11 @@ def python_reloader(main_func, args, kwargs):
             pass
 
 
-def jython_reloader(main_func, args, kwargs):
-    from _systemrestart import SystemRestart
-    _thread.start_new_thread(main_func, args)
-    while True:
-        if code_changed():
-            raise SystemRestart
-        time.sleep(1)
-
-
 def main(main_func, args=None, kwargs=None):
     if args is None:
         args = ()
     if kwargs is None:
         kwargs = {}
-    if sys.platform.startswith('java'):
-        reloader = jython_reloader
-    else:
-        reloader = python_reloader
 
     wrapped_main_func = check_errors(main_func)
-    reloader(wrapped_main_func, args, kwargs)
+    python_reloader(wrapped_main_func, args, kwargs)
diff --git a/docs/howto/jython.txt b/docs/howto/jython.txt
index cdb9b06caf..9685ba2bb0 100644
--- a/docs/howto/jython.txt
+++ b/docs/howto/jython.txt
@@ -1,74 +1,14 @@
-========================
-Running Django on Jython
-========================
+================
+Django on Jython
+================
 
 .. index:: Jython, Java, JVM
 
 Jython_ is an implementation of Python that runs on the Java platform (JVM).
-This document will get you up and running with Django on top of Jython.
-
-Installing Jython
-=================
-
-Django works with Jython versions 2.7b2 and higher. See the Jython_ website for
-download and installation instructions.
 
 .. _jython: http://www.jython.org/
 
-Creating a servlet container
-============================
-
-If you just want to experiment with Django, skip ahead to the next section;
-Django includes a lightweight Web server you can use for testing, so you won't
-need to set up anything else until you're ready to deploy Django in production.
-
-If you want to use Django on a production site, use a Java servlet container,
-such as `Apache Tomcat`_. Full JavaEE applications servers such as `GlassFish`_
-or `JBoss`_ are also OK, if you need the extra features they include.
-
-.. _`Apache Tomcat`: https://tomcat.apache.org/
-.. _GlassFish: https://javaee.github.io/glassfish/
-.. _JBoss: https://www.jboss.org/
-
-Installing Django
-=================
-
-The next step is to install Django itself. This is exactly the same as
-installing Django on standard Python, so see
-:ref:`removing-old-versions-of-django` and :ref:`install-django-code` for
-instructions.
-
-Installing Jython platform support libraries
-============================================
-
-The `django-jython`_ project contains database backends and management commands
-for Django/Jython development. Note that the builtin Django backends won't work
-on top of Jython.
-
-.. _`django-jython`: https://github.com/beachmachine/django-jython
-
-To install it, follow the `installation instructions`_ detailed on the project
-website. Also, read the `database backends`_ documentation there.
-
-.. _`installation instructions`: https://pythonhosted.org/django-jython/quickstart.html#install
-.. _`database backends`: https://pythonhosted.org/django-jython/database-backends.html
-
-Differences with Django on Jython
-=================================
-
-.. index:: JYTHONPATH
-
-At this point, Django on Jython should behave nearly identically to Django
-running on standard Python. However, are a few differences to keep in mind:
-
-* Remember to use the ``jython`` command instead of ``python``. The
-  documentation uses ``python`` for consistency, but if you're using Jython
-  you'll want to mentally replace ``python`` with ``jython`` every time it
-  occurs.
-
-* Similarly, you'll need to use the ``JYTHONPATH`` environment variable
-  instead of ``PYTHONPATH``.
-
-* Any part of Django that requires `Pillow`_ will not work.
-
-.. _Pillow: https://pillow.readthedocs.io/en/latest/
+If you want to use Jython (which supports only Python 2.7 at the time of this
+writing), you must use Django 1.11.x (the last series to support Python 2).
+Jython support may be readded to Django if a Python 3 compatible Jython is
+released.
diff --git a/docs/index.txt b/docs/index.txt
index a764ee1be1..6ab9fdb4c5 100644
--- a/docs/index.txt
+++ b/docs/index.txt
@@ -275,14 +275,6 @@ more efficiently - faster, and using fewer system resources.
 
 * :doc:`Performance and optimization overview <topics/performance>`
 
-Python compatibility
-====================
-
-Django aims to be compatible with multiple different flavors and versions of
-Python:
-
-* :doc:`Jython support <howto/jython>`
-
 Geographic framework
 ====================
 
diff --git a/docs/intro/install.txt b/docs/intro/install.txt
index 9861923b37..a0e7f54562 100644
--- a/docs/intro/install.txt
+++ b/docs/intro/install.txt
@@ -19,13 +19,6 @@ database called SQLite_ so you won't need to set up a database just yet.
 Get the latest version of Python at https://www.python.org/downloads/ or with
 your operating system's package manager.
 
-.. admonition:: Django on Jython
-
-    If you use Jython_ (a Python implementation for the Java platform), you'll
-    need to follow a few additional steps. See :doc:`/howto/jython` for details.
-
-.. _jython: http://www.jython.org/
-
 You can verify that Python is installed by typing ``python`` from your shell;
 you should see something like::
 
diff --git a/docs/releases/1.0.txt b/docs/releases/1.0.txt
index 65c185e82a..0c24ca3fb9 100644
--- a/docs/releases/1.0.txt
+++ b/docs/releases/1.0.txt
@@ -154,8 +154,6 @@ Django's codebase has been refactored to remove incompatibilities with
 on the Java Virtual Machine. Django is now compatible with the forthcoming
 Jython 2.5 release.
 
-See :doc:`/howto/jython`.
-
 .. _Jython: http://www.jython.org/
 
 Generic relations in forms and admin
diff --git a/docs/topics/install.txt b/docs/topics/install.txt
index 60affd4f29..ab6b41a3ee 100644
--- a/docs/topics/install.txt
+++ b/docs/topics/install.txt
@@ -15,10 +15,10 @@ your operating system's package manager.
 
 .. admonition:: Django on Jython
 
-    If you use Jython_ (a Python implementation for the Java platform), you'll
-    need to follow a few additional steps. See :doc:`/howto/jython` for details.
+    Jython_ (a Python implementation for the Java platform) is not compatible
+    with Python 3, so Django ≥ 2.0 cannot run on Jython.
 
-.. _jython: http://jython.org/
+.. _jython: http://www.jython.org/
 
 .. admonition:: Python on Windows
 
diff --git a/tests/admin_scripts/tests.py b/tests/admin_scripts/tests.py
index 8fd564468d..4617978947 100644
--- a/tests/admin_scripts/tests.py
+++ b/tests/admin_scripts/tests.py
@@ -95,15 +95,8 @@ class AdminScriptTestCase(unittest.TestCase):
         else:
             os.remove(full_name)
 
-        # Also try to remove the compiled file; if it exists, it could
+        # Also remove a __pycache__ directory, if it exists; it could
         # mess up later tests that depend upon the .py file not existing
-        try:
-            if sys.platform.startswith('java'):
-                # Jython produces module$py.class files
-                os.remove(re.sub(r'\.py$', '$py.class', full_name))
-        except OSError:
-            pass
-        # Also remove a __pycache__ directory, if it exists
         cache_name = os.path.join(self.test_dir, '__pycache__')
         if os.path.isdir(cache_name):
             shutil.rmtree(cache_name)
@@ -133,11 +126,6 @@ class AdminScriptTestCase(unittest.TestCase):
 
         # Define a temporary environment for the subprocess
         test_environ = os.environ.copy()
-        if sys.platform.startswith('java'):
-            python_path_var_name = 'JYTHONPATH'
-        else:
-            python_path_var_name = 'PYTHONPATH'
-
         old_cwd = os.getcwd()
 
         # Set the test environment
@@ -147,7 +135,7 @@ class AdminScriptTestCase(unittest.TestCase):
             del test_environ['DJANGO_SETTINGS_MODULE']
         python_path = [base_dir, django_dir, tests_dir]
         python_path.extend(ext_backend_base_dirs)
-        test_environ[python_path_var_name] = os.pathsep.join(python_path)
+        test_environ['PYTHONPATH'] = os.pathsep.join(python_path)
         test_environ['PYTHONWARNINGS'] = ''
 
         # Move to the test directory and run