Fix broken hash function hashbpcharextended().

Ignore trailing spaces for non-deterministic collations when
hashing.

The previous behavior could lead to tuples falling into the wrong
partitions when hash partitioning is combined with the BPCHAR type and
a non-deterministic collation. Fortunately, it did not affect hash
indexes, because hash indexes do not use extended hash functions.

Decline to backpatch, per discussion.

Discussion: https://postgr.es/m/[email protected]
Reviewed-by: Richard Guo, Tom Lane

Author: jeff-davis

src/backend/utils/adt/varchar.c

@@ -1086,7 +1086,7 @@ hashbpcharextended(PG_FUNCTION_ARGS)
 			Size		bsize;
 			uint8_t    *buf;
 
-			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
 
 			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
 									uchar, ulen, NULL, 0);