This is particularily useful for “gnt-cluster redist-conf”, but
also for all other cases where the configuration files are
rewritten on other nodes.

$ gnt-cluster redist-conf
… Copy of file /var/lib/ganeti/config.data to node … failed: Error while
executing backend function: [Errno 1] Operation not permitted
… Error while uploading ssconf files to node …: Error while executing backend
function: [Errno 1] Operation not permitted

$ gnt-node modify --offline no --force node3.example.com
… - WARNING: Not enough master candidates (desired 10, new value will be 4)
… Copy of file /var/lib/ganeti/config.data to node node8.example.com failed:
Error while executing backend function: [Errno 1] Operation not permitted
Modified node node3.example.com
 - offline -> True
 - master_candidate -> auto-demotion due to offline

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>