For system backup&restore function, some files can't be restore

[Eason]

For system backup&restore function, some files can't be restore .

系统备份恢复功能中，有些文件无法被恢复。那为何要备份这些文件？

Steps:
1. Enter into system settings-->Backups
2. Click "Back Up Now.." to backup the system, during backup system, pls set a password.
3. After backup completely, click "Restore.." button in Backups page
-->Failed. Prompt some files can't be restore

Configuration:
PC: Dell Vostro
OS: Ubuntu Kylin 14.04 Trusty Daily Build 1009