Version check between oned head node and physical hosts
while upgrading from 2.2 -> 3.0 i think i had a situation
where the head node was already on 3.0, and the hosts
had a mix of 2.2 and 3.0 probes, resulting in problems
where different numbers of arguments were required.
ONE should make sure to talk to only matching hosts,
where that could be determined either by the ONE version,
or even an ABI version, which has to change whenever
something changes in the syntax or semantics of the calls.
This could be part of the monitoring, and could set
a host state MISMATCH (with more verbose message in the logs)
if something is wrong.