The query lifetime expression context created in
hypothetical_dense_rank_final() was buggily allocated in the calling
memory context. I (Andres) broke that in bf6c614a.

Reported-By: Rajkumar Raghuwanshi
Author: Amit Langote
Discussion:  https://postgr.es/m/CAKcux6kmzWmur5HhA_aU6gYVFu0RLQdgJJ+aC9SLdcOvBSrpfA@mail.gmail.com
Backpatch: 11-