tablesample test failure with small TOAST_TUPLE_THRESHOLD

Today, I tried compiling with:

-#define TOAST_TUPLE_THRESHOLD   MaximumBytesPerTuple(TOAST_TUPLES_PER_PAGE)
+#define TOAST_TUPLE_THRESHOLD   100

Most of the regression tests pass just fine, but the tablesample one
experiences numerous failures.  For example:
 SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (0);  id ----
!   3
!   4
!   5
!   6
!   7
!   8
! (6 rows)
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (0);  id
--- 5,11 ---- SELECT t.id FROM test_tablesample AS t TABLESAMPLE SYSTEM (50) REPEATABLE (0);  id ----
! (0 rows)
 SELECT id FROM test_tablesample TABLESAMPLE SYSTEM (100.0/11) REPEATABLE (0);  id

Most of the failures are due to table-sampling that previously
returned rows no longer returning any rows.  I don't know why that
should happen, or whether it's expected.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company