`interfaces_synchronize` idempotence

Summary

interfaces_synchronize action is not idempotent.

Steps to reproduce

Just run this action two times.

Expected behavior

No changes made when executing for the second time.

Actual behavior

Always one change is made.

Relevant logs and/or screenshots

 ___________________________________________________________
/ TASK [networking : waiting for network interfaces restart \
\ to finish]                                                /
 -----------------------------------------------------------
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

Friday 13 April 2018  13:43:18 +0200 (0:00:00.647)       0:00:37.983 ********** 
changed: [core01]
changed: [compute005]
changed: [compute007]

Possible fixes

add changed_when to command module.