[1.8.x] Sorted imports with isort; refs #23860.

Backport of 0ed7d15563 from master

tests/migrations/test_operations.py

@@ -2,11 +2,6 @@ from __future__ import unicode_literals
 
 import unittest
 
-try:
-    import sqlparse
-except ImportError:
-    sqlparse = None
-
 from django.db import connection, migrations, models, transaction
 from django.db.migrations.migration import Migration
 from django.db.migrations.state import ProjectState
@@ -19,6 +14,11 @@ from django.utils import six
 from .models import FoodManager, FoodQuerySet
 from .test_base import MigrationTestBase
 
+try:
+    import sqlparse
+except ImportError:
+    sqlparse = None
+
 
 class OperationTestBase(MigrationTestBase):
     """