莫名其妙的错误。
删除了migreation文件，并且更换了数据库。
1.直接makemigrations + migrate error: no change ?? WTF
2.makemigrations app + migrate app 循环完成 no error, but can't use this project. WTF +1
3.makemigrations app1 + makemigrations app2 ... migrate oh, success. what's happend ?