After I started my Huawei P9 Lite for the first time, after I completed the first boot setup, it asked me the following question:
What does it mean? It is the first time I run Android M ever and never encountered such a question before.
I think it is related to Google backup. If you setup your Google account then this option asks you to restore your backup : phone numbers, apps as well as settings, such as APN, WiFi passwords, and so.
UPDATE : I've found that the step for restoring defaults is a part of the setup process and it is optional. You will be asked about restoring all default settings. Just tap Do not allow.