Avoided using BinaryField unecessarily in tests.

Several database backends struggle with binary data. This change
minimizes the risk of unrelated tests failures when binary fields
trigger errors.

Forward-port of 2e4bcb9b from stable/1.7.x.

tests/backends/models.py

@@ -64,7 +64,6 @@ class Post(models.Model):
 class Reporter(models.Model):
     first_name = models.CharField(max_length=30)
     last_name = models.CharField(max_length=30)
-    raw_data = models.BinaryField()
 
     def __str__(self):
         return "%s %s" % (self.first_name, self.last_name)
@@ -112,3 +111,7 @@ class ObjectReference(models.Model):
 
     def __str__(self):
         return str(self.obj_id)
+
+
+class RawData(models.Model):
+    raw_data = models.BinaryField()

tests/backends/tests.py

@@ -334,9 +334,9 @@ class LastExecutedQueryTest(TestCase):
         """
         Test that last_executed_query() returns an Unicode string
         """
-        persons = models.Reporter.objects.filter(raw_data=b'\x00\x46  \xFE').extra(select={'föö': 1})
-        sql, params = persons.query.sql_with_params()
-        cursor = persons.query.get_compiler('default').execute_sql(CURSOR)
+        data = models.RawData.objects.filter(raw_data=b'\x00\x46  \xFE').extra(select={'föö': 1})
+        sql, params = data.query.sql_with_params()
+        cursor = data.query.get_compiler('default').execute_sql(CURSOR)
         last_sql = cursor.db.ops.last_executed_query(cursor, sql, params)
         self.assertIsInstance(last_sql, six.text_type)