deja-dup backups fail for a domain user

[François Guerraz]

(initially reported on https://bugzilla.redhat.com/show_bug.cgi?id=996106)

Fedora release 19 (Schrödinger’s Cat)
deja-dup-26.0-1.fc19.x86_64
duplicity-0.6.22-1.fc19.x86_64

Description of problem:
When a domain user (domain joined with realmd, standard config) tries to use deja-dup, the backup fails completely.

How reproducible:
All the time

Steps to Reproduce:
1. Join a domain
2. Login with a user domain
3. set-up a backup with duplicity

Actual results:
says something about being unable to restore the metadata

Expected results:
Should back up your files

Additional info:
The problem is that by default, realmd creates a /home/<domain>/<user> home directory. /home/<domain> is owned by root:root and has only rwx-x-x rights and deja-dup is silly enough to unnecessarily want to read this diectory to make the diff instead of reading the *real* user's home directory which is fully readable and accessible:

DUPLICITY: DEBUG 1
DUPLICITY: . Comparing () and ()

DUPLICITY: DEBUG 1
DUPLICITY: . Selecting /home

DUPLICITY: DEBUG 1
DUPLICITY: . Comparing ('home',) and ('home',)

DUPLICITY: WARNING 10 '/home/<domain>'
DUPLICITY: . Error accessing possibly locked file /home/<domain>

DUPLICITY: WARNING 10 '/home/lost+found'
DUPLICITY: . Error accessing possibly locked file /home/lost+found

DUPLICITY: WARNING 10 '/lost+found'
DUPLICITY: . Error accessing possibly locked file /lost+found

DUPLICITY: WARNING 10 '/root'
DUPLICITY: . Error accessing possibly locked file /root

giving read access on /home/<domain> to everyone fixes the problem.