Fix new GIST build code to work under CLOBBER_CACHE_ALWAYS.
Can't say if this fixes *all* cases, but at least we get through
the "point" regression test now, which hyrax's last run did not.
Report:
@@ -408,6 +408,7 @@ gist_indexsortbuild(GISTBuildState *state)
* replaced with the real root page at the end.
*/
page = palloc0(BLCKSZ);
+ RelationOpenSmgr(state->indexrel);
smgrextend(state->indexrel->rd_smgr, MAIN_FORKNUM, GIST_ROOT_BLKNO,
page, true);
state->pages_allocated++;
