I had previously updated my script to make use of the documented -n flag,
but hadn't restarted it yet. Perhaps that may also do the same thing I
did, explictly redirecting stdin to /dev/null.
I've also now used -o PasswordAuthentication=no.
Until I recreate the situation again next time the remote network and nfs
server fails, I can't know whether the -n flag will work around this bug.
"I give up," said Pierre de Fermat's friend. "How DO you keep a
mathematician busy for 350 years?"