Hi,
Andres asked me on IRC to report this here. Since we upgraded our
standby servers to 9.1.15 (though the master is still running 9.1.14),
we've seen the error in $SUBJECT a number of times. I managed to
reproduce it today by running the same query over and over again, and
attached is the back trace.
Let me know if you need any additional information.
.m