M-Lab wants an IPv4 and IPv6 address assigned per slice. When more than one interface is added to a slice, the interface/X/ip argument gets filled out correctly but the slice will not start because the 'nodev' option is missing.
i = 0
for a in addresses.split(","):
self.config.update("interfaces/%d/ip" % i, a)
i = 0
for a in addresses.split(","):
self.config.update("interfaces/%d/ip" % i, a)
+ self.config.update("interfaces/%d/nodev" % i, "")
i += 1
while self.config.unset("interfaces/%d/ip" % i):
i += 1
i += 1
while self.config.unset("interfaces/%d/ip" % i):
i += 1