[1.7.x] Fixed #22487: Separated schema migration from data migration in test

The data migration failed on Oracle, killing the entire test suite.

Thanks timo for reporting the Oracle breakage,
and andrewgodwin for suggesting the solution.

Backport of 64d94cf from master

tests/migration_test_data_persistence/migrations/0001_initial.py

@@ -4,14 +4,6 @@ from __future__ import unicode_literals
 from django.db import models, migrations
 
 
-def add_book(apps, schema_editor):
-    apps.get_model("migration_test_data_persistence", "Book").objects.using(
-        schema_editor.connection.alias,
-    ).create(
-        title="I Love Django",
-    )
-
-
 class Migration(migrations.Migration):
 
     dependencies = [
@@ -28,7 +20,4 @@ class Migration(migrations.Migration):
             },
             bases=(models.Model,),
         ),
-        migrations.RunPython(
-            add_book,
-        ),
     ]

tests/migration_test_data_persistence/migrations/0002_add_book.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+def add_book(apps, schema_editor):
+    apps.get_model("migration_test_data_persistence", "Book").objects.using(
+        schema_editor.connection.alias,
+    ).create(
+        title="I Love Django",
+    )
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migration_test_data_persistence", "0001_initial")]
+
+    operations = [
+        migrations.RunPython(
+            add_book,
+        ),
+    ]