Cannot set a timezone on dragonboard core system

Using snapweb to set a correct local time.

$ timedatectl
      Local time: Thu 2017-03-16 10:03:19 EDT
  Universal time: Thu 2017-03-16 14:03:19 UTC
        RTC time: Wed 1970-01-14 20:06:13
       Time zone: America/New_York (EDT, -0400)
 Network time on: yes
NTP synchronized: yes
 RTC in local TZ: no

The service overrides it and reports an error

ar 16 14:06:27 patsdragon dbus[1683]: [system] Activating via systemd: service name='org.freedesktop.timedate1' unit='dbus-org.freedesktop.timedate1.service'
Mar 16 14:06:27 patsdragon systemd[1]: Starting Time & Date Service...
Mar 16 14:06:27 patsdragon dbus[1683]: [system] Successfully activated service 'org.freedesktop.timedate1'
Mar 16 14:06:27 patsdragon systemd-timedated[7428]: /etc/localtime should be a symbolic link to a time zone data file in /usr/share/zoneinfo/.
Mar 16 14:06:27 patsdragon systemd[1]: Started Time & Date Service.

Time is reset to UTC

pat-mcgowan@patsdragon:~$ timedatectl
      Local time: Thu 2017-03-16 14:06:27 UTC
  Universal time: Thu 2017-03-16 14:06:27 UTC
        RTC time: Wed 1970-01-14 20:09:21
       Time zone: n/a (UTC, +0000)
 Network time on: yes
NTP synchronized: yes
 RTC in local TZ: no

Localtime file does seem linked indirectly to a zoneinfo file

$ ls -l /etc/localtime
lrwxrwxrwx 1 root root 18 Mar 8 15:03 /etc/localtime -> writable/localtime
$ ls -l /etc/writable/localtime
lrwxrwxrwx 1 root root 38 Mar 16 14:02 /etc/writable/localtime -> ../usr/share/zoneinfo/America/New_York