As you can see in an XXX comment in the libpq test program, the current
implementation has the behavior that PQgetResult() returns NULL after a
batch is finished and has reported PGRES_BATCH_END. I don't know if
there's a hard reason to do that, but I'd like to supress it because it
seems weird and out of place.
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Álvaro Herrera 39°49'30"S 73°17'W