and now sshdport). First off, take the DB out of the loop. There is no
reason to do DB locking since local nodes are not shared, and even if
they were, we now allocate port ranges to each experiment when it uses
virtual nodes (which is the only way to share a node anyway), so there
is never a case that port allocation between experiments has to be
coordinated. The only locking that is done is when the range is
allocated to the experiment, buts that done only once, and only if the
experiment uses virtual nodes (local or remote).

Also, now that its easy to create lots of jails on a single node, its
a good idea to give each one their own ssh port. This is recorded in
the DB nodes table (sshdport) and returned in the jail config from
tmcd.