mounting an NFS share via curtin_userdata

[G_Gold]

Greetings, list. 

I'm trying to accomplish a seemingly simple task, with little
success. 
The goal is to have a node boot after deployment with an NFS
share mounted. (The NFS server is a system within the node's
LAN). 

I've tried multiple directives within /etc/maas/presseed/curtin_userdata , 
the last  one being:

  mount_share:["curtin", "in-target", "--", "sh", "-c", "/bin/echo '192.168.1.1:/data /data nfs _netdev,rw 0 0'  >> /etc/fstab"]

However, the node still boots with the share not mounted,
while mounting manually works with no issues. 

Thank you. 

-- 
G.Gold