[1.7.x] Fixed #22539 -- Copied exclude argument in Model.full_clean() to prevent side effects.

Backport of e2e4cdba11 from master

3 files changed, 11 insertions, 2 deletions

diff --git a/django/db/models/base.py b/django/db/models/base.py
index f156643eed..cee5b9a520 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -987,6 +987,8 @@ class Model(six.with_metaclass(ModelBase)):
         errors = {}
         if exclude is None:
             exclude = []
+        else:
+            exclude = list(exclude)
 
         try:
             self.clean_fields(exclude=exclude)
diff --git a/tests/validation/__init__.py b/tests/validation/__init__.py
index ba35963744..01575c1b10 100644
--- a/tests/validation/__init__.py
+++ b/tests/validation/__init__.py
@@ -3,9 +3,9 @@ from django.test import TestCase
 
 
 class ValidationTestCase(TestCase):
-    def assertFailsValidation(self, clean, failed_fields):
+    def assertFailsValidation(self, clean, failed_fields, **kwargs):
         with self.assertRaises(ValidationError) as cm:
-            clean()
+            clean(**kwargs)
         self.assertEqual(sorted(failed_fields), sorted(cm.exception.message_dict))
 
     def assertFieldFailsValidationWithMessage(self, clean, field_name, message):
diff --git a/tests/validation/tests.py b/tests/validation/tests.py
index 7f81cafccf..6122444e3d 100644
--- a/tests/validation/tests.py
+++ b/tests/validation/tests.py
@@ -59,6 +59,13 @@ class BaseModelValidationTests(ValidationTestCase):
         mtv = ModelToValidate(number=10, name='Some Name', slug='##invalid##')
         self.assertFailsValidation(mtv.full_clean, ['slug'])
 
+    def test_full_clean_does_not_mutate_exclude(self):
+        mtv = ModelToValidate(f_with_custom_validator=42)
+        exclude = ['number']
+        self.assertFailsValidation(mtv.full_clean, ['name'], exclude=exclude)
+        self.assertEqual(len(exclude), 1)
+        self.assertEqual(exclude[0], 'number')
+
 
 class ArticleForm(forms.ModelForm):
     class Meta: