From f1664a27345d09b91892cbaa46a7ab73bd62b219 Mon Sep 17 00:00:00 2001
From: Nick Pope <nick.pope@flightdataservices.com>
Date: Thu, 6 Oct 2016 11:02:48 +0100
Subject: [PATCH] Replaced '__' with LOOKUP_SEP constant.

---
 django/contrib/admin/checks.py               | 3 ++-
 django/contrib/admin/utils.py                | 2 +-
 django/core/management/commands/inspectdb.py | 9 +++++----
 django/db/models/base.py                     | 2 +-
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/django/contrib/admin/checks.py b/django/contrib/admin/checks.py
index d61ce723e36..1d802d2fbe7 100644
--- a/django/contrib/admin/checks.py
+++ b/django/contrib/admin/checks.py
@@ -11,6 +11,7 @@ from django.contrib.admin.utils import (
 from django.core import checks
 from django.core.exceptions import FieldDoesNotExist
 from django.db import models
+from django.db.models.constants import LOOKUP_SEP
 from django.forms.models import (
     BaseModelForm, BaseModelFormSet, _get_foreign_key,
 )
@@ -458,7 +459,7 @@ class BaseModelAdminChecks(object):
             ]
         elif field_name == '?':
             return []
-        elif '__' in field_name:
+        elif LOOKUP_SEP in field_name:
             # Skip ordering in the format field1__field2 (FIXME: checking
             # this format would be nice, but it's a little fiddly).
             return []
diff --git a/django/contrib/admin/utils.py b/django/contrib/admin/utils.py
index 6b5b05e3b2c..1e13d13d31b 100644
--- a/django/contrib/admin/utils.py
+++ b/django/contrib/admin/utils.py
@@ -30,7 +30,7 @@ def lookup_needs_distinct(opts, lookup_path):
     """
     Returns True if 'distinct()' should be used to query the given lookup path.
     """
-    lookup_fields = lookup_path.split('__')
+    lookup_fields = lookup_path.split(LOOKUP_SEP)
     # Remove the last item of the lookup path if it is a query term
     if lookup_fields[-1] in QUERY_TERMS:
         lookup_fields = lookup_fields[:-1]
diff --git a/django/core/management/commands/inspectdb.py b/django/core/management/commands/inspectdb.py
index 31079c1a479..69721b1283a 100644
--- a/django/core/management/commands/inspectdb.py
+++ b/django/core/management/commands/inspectdb.py
@@ -6,6 +6,7 @@ from collections import OrderedDict
 
 from django.core.management.base import BaseCommand, CommandError
 from django.db import DEFAULT_DB_ALIAS, connections
+from django.db.models.constants import LOOKUP_SEP
 from django.utils.encoding import force_text
 
 
@@ -189,10 +190,10 @@ class Command(BaseCommand):
         if num_repl > 0:
             field_notes.append('Field renamed to remove unsuitable characters.')
 
-        if new_name.find('__') >= 0:
-            while new_name.find('__') >= 0:
-                new_name = new_name.replace('__', '_')
-            if col_name.lower().find('__') >= 0:
+        if new_name.find(LOOKUP_SEP) >= 0:
+            while new_name.find(LOOKUP_SEP) >= 0:
+                new_name = new_name.replace(LOOKUP_SEP, '_')
+            if col_name.lower().find(LOOKUP_SEP) >= 0:
                 # Only add the comment if the double underscore was in the original name
                 field_notes.append("Field renamed because it contained more than one '_' in a row.")
 
diff --git a/django/db/models/base.py b/django/db/models/base.py
index e15ca006092..e7b3f3fd71d 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -1617,7 +1617,7 @@ class Model(six.with_metaclass(ModelBase)):
 
         # Skip ordering in the format field1__field2 (FIXME: checking
         # this format would be nice, but it's a little fiddly).
-        fields = (f for f in fields if '__' not in f)
+        fields = (f for f in fields if LOOKUP_SEP not in f)
 
         # Skip ordering on pk. This is always a valid order_by field
         # but is an alias and therefore won't be found by opts.get_field.