Fixed ModelState breaking when unique_together has unhashable elements.

django/db/migrations/state.py

@@ -1,6 +1,6 @@
 from django.db import models
 from django.db.models.loading import BaseAppCache
-from django.db.models.options import DEFAULT_NAMES
+from django.db.models.options import DEFAULT_NAMES, normalize_unique_together
 from django.utils import six
 from django.utils.module_loading import import_by_path
 
@@ -127,7 +127,8 @@ class ModelState(object):
                 continue
             elif name in model._meta.original_attrs:
                 if name == "unique_together":
-                    options[name] = set(model._meta.original_attrs["unique_together"])
+                    ut = model._meta.original_attrs["unique_together"]
+                    options[name] = set(normalize_unique_together(ut))
                 else:
                     options[name] = model._meta.original_attrs[name]
         # Make our record

django/db/models/options.py

@@ -32,10 +32,13 @@ def normalize_unique_together(unique_together):
     tuple of two strings. Normalize it to a tuple of tuples, so that
     calling code can uniformly expect that.
     """
-    unique_together = tuple(unique_together)
-    if unique_together and not isinstance(unique_together[0], (tuple, list)):
+    if not unique_together:
+        return ()
+    first_element = next(iter(unique_together))
+    if not isinstance(first_element, (tuple, list)):
         unique_together = (unique_together,)
-    return unique_together
+    # Normalize everything to tuples
+    return tuple(tuple(ut) for ut in unique_together)
 
 
 @python_2_unicode_compatible

tests/migrations/test_state.py

@@ -55,7 +55,7 @@ class StateTests(TestCase):
         self.assertEqual(author_state.fields[1][1].max_length, 255)
         self.assertEqual(author_state.fields[2][1].null, False)
         self.assertEqual(author_state.fields[3][1].null, True)
-        self.assertEqual(author_state.options, {"unique_together": set(("name", "bio"))})
+        self.assertEqual(author_state.options, {"unique_together": {("name", "bio")}})
         self.assertEqual(author_state.bases, (models.Model, ))
 
         self.assertEqual(book_state.app_label, "migrations")