In-place package upgrade of sown-core breaks node

[TimStallard]

We seem to do a lot of initial config inside postinst, which runs after an upgrade. This produces a load of output and leaves the node in a state running the initial install scripts:

root@node310:~# opkg upgrade sown-core
Upgrading sown-core on root from 0.9-2016 to 0.91-2016...
Downloading http://[2001:630:d0:f700::223]/tds/mips_24kc/sown/sown-core_0.91-2016_mips_24kc.ipk
iptables v1.6.2: can't initialize iptables table `raw': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
iptables v1.6.2: can't initialize iptables table `raw': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
ip6tables v1.6.2: can't initialize ip6tables table `raw': Table does not exist (do you need to insmod?)
Perhaps ip6tables or your kernel needs to be upgraded.
ip6tables v1.6.2: can't initialize ip6tables table `raw': Table does not exist (do you need to insmod?)
Perhaps ip6tables or your kernel needs to be upgraded.
Configuring sown-core.
iptables v1.6.2: can't initialize iptables table `raw': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
iptables v1.6.2: can't initialize iptables table `raw': Table does not exist (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
ip6tables v1.6.2: can't initialize ip6tables table `raw': Table does not exist (do you need to insmod?)
Perhaps ip6tables or your kernel needs to be upgraded.
ip6tables v1.6.2: can't initialize ip6tables table `raw': Table does not exist (do you need to insmod?)
Perhaps ip6tables or your kernel needs to be upgraded.
Loading ip blacklist
uci: Entry not found
Layer7 not yet supported
Loading port filter
uci: Entry not found
Loading NAT
Forbidding private subnet access
White listing DNS and BOOTP traffic
Creating table for one-ip-per-mac restrictions
date: invalid date ‘201107010000’
sh: -lt: argument expected
Collected errors:
 * resolve_conffiles: Existing conffile /etc/config/sown_core is different from the conffile in the new package. The new conffile will be placed at /etc/config/sown_core-opkg.
root@node310:~# crontab -l
# DO NOT EDIT THE CRONTAB HERE
# It is automatically generated from /etc/sown/configure_scripts/available/crontabs
# which in turn is generated at boot
*/5 * * * * /etc/sown/configure_scripts/available/credentials