OH2 OneWire wants a host name - suspected snapshot build 837 problem

I’ve just installed the onewire binding on OH2 and it keeps putting a host name is null error in the logs. In the config file there is a space for the IP address of owserver but no host name entry, and it suggests not using “localhost” to prevent unnecessary hostfile lookups. I’m accessing owserver on another system.
This may be a problem with snapshot build 837, as I’ve just installed V2,0 Stable into another folder, set the parameters for onewire in onewire.cfg, deliberately ignored the onewire binding settings in paperui, and the fault is no longer there.
There is a chance the issue is connected with double configurations, one from paperui and one from services\onewire.cfg, as I originally used paperui to configure it.

Further information.
The error from Karaf console

Exception in thread "OneWireBinding/ReaderTask" java.lang.IllegalArgumentException: hostname can't be null
    at java.net.InetSocketAddress.checkHost(Unknown Source)
    at java.net.InetSocketAddress.<init>(Unknown Source)
    at org.owfs.jowfsclient.internal.OwfsConnectionImpl.tryToSocketConnectionAndStreamsInitialization(OwfsConnectionImpl.java:79)
    at org.owfs.jowfsclient.internal.OwfsConnectionImpl.connect(OwfsConnectionImpl.java:70)
    at org.owfs.jowfsclient.internal.OwfsConnectionImpl.establishConnectionIfNeeded(OwfsConnectionImpl.java:113)
    at org.owfs.jowfsclient.internal.OwfsConnectionImpl.sendRequest(OwfsConnectionImpl.java:204)
    at org.owfs.jowfsclient.internal.OwfsConnectionImpl.exists(OwfsConnectionImpl.java:158)
    at org.openhab.binding.onewire.internal.connection.OneWireConnection.checkIfDeviceExists(OneWireConnection.java:273)
    at org.openhab.binding.onewire.internal.connection.OneWireConnection.readFromOneWire(OneWireConnection.java:290)
    at org.openhab.binding.onewire.internal.OneWireBinding.updateItemFromOneWire(OneWireBinding.java:304)
    at org.openhab.binding.onewire.internal.OneWireBinding.devicePropertyWantsUpdate(OneWireBinding.java:258)
    at org.openhab.binding.onewire.internal.scheduler.OneWireUpdateTask.run(OneWireUpdateTask.java:61)

The error appears on the next reboot after the binding has been installed in debug mode. Setting a hostname in the config file makes no difference, even though it can be seen in Karaf with “config:property-list”