Commit 6df7a9698 wrote appendPQExpBuffer where it should have
written printfPQExpBuffer. This resulted in re-issuing the
previous query along with the desired one, which very accidentally
had no negative consequences except for some wasted cycles.
Back-patch to v14 where that came in.
Discussion: https://postgr.es/m/1714711.1642962663@sss.pgh.pa.us