修复数据库已有用户problems_statu字段为空造成的问题

account/migrations/0004_remove_user_problems_status.py

@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('account', '0003_auto_20150915_2025'),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name='user',
+            name='problems_status',
+        ),
+    ]