Fix counter-intuitive backup API

[alexAubin]

The problem

c.f. YunoHost/issues#1102

Currently there are some counter-intuitive behaviors with backup create and backup restore.

Typically, yunohost backup create --apps wordpress will backup wordpress and the whole system. You need to explicitly add --ignore-system at the end. Similarly, yunohost backup create --system ldap will backup the ldap base and all the apps. This kind of stuff also apply for the restore, so yunohost backup restore --apps wordpress will restore wordpress and all the system ...

This would be nice to have this fix for stretch as we can expect several people to be willing to use the backup/restore instead of the straight migration.

Solution

• (Remove old deprecated --hooks options)
• Remove --ignore-system and --ignore-apps
• Only backup/restore what is explicitly given in argument (or everything if neither --apps or --system are given)

To clarify, here's a table summarizing the behavior for a few example :

Commnand	Behavior
yunohost backup create	Create a backup of everything (apps and system)
yunohost backup create --apps	Create a backup of all apps (no system)
yunohost backup create --apps wordpress	Create a backup of wordpress only
yunohost backup create --apps wordpress --system	Create a backup of wordpress only + all the system
yunohost backup create --apps wordpress --system ldap	Create a backup of wordpress only + ldap base

(Same kind of behavior for restore)

PR Status

To be tested

How to test

Pull the branch and maybe add some debug info + a return to see what it would do without actually doing it ...

Validation

• Principle agreement 0/2 :
• Quick review 0/1 :
• Simple test 0/1 :
• Deep review 0/1 :

[Psycojoker]

Principle approval.

(while I'm not sure it's the good time to do that)

[zamentur]

LGTM, untested. I will test it with my new borg_ynh apps