Parsed test spec with 3 sessions

starting permutation: s1b s1q s2s s2f s2w s2n s2i s2p s1q s2r s2m s1q s1c s3q
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
step s1q: SET enable_seqscan = off; SELECT count(*) AS seed_docs FROM iso_dir WHERE body @@> 'seed';
seed_docs
---------
      200
(1 row)

step s2s: LOAD 'pg_sift'; SET sift.async_maintenance = off; SET client_min_messages = error; SET sift.test_limits = 'max_segments=64';
step s2f: SET sift.test_fail_pages = 1;
step s2w: DO $$ BEGIN FOR i IN 1..90 LOOP INSERT INTO iso_dir (body) SELECT 'room ' || iso_big(i); END LOOP; END $$;
step s2n: SELECT count(*) = 64 AS at_limit, count(*) FILTER (WHERE kind = 'buffer') AS open_buffers FROM sift.segments('iso_dir_idx');
at_limit|open_buffers
--------+------------
t       |           1
(1 row)

step s2i: INSERT INTO iso_dir (body) SELECT 'room more ' || iso_big(1000 + g) FROM generate_series(1, 5) g;
step s2p: SELECT sift.promote('iso_dir_idx') >= 0 AS promoted;
ERROR:  sift test: injected failure after 1 pages
step s1q: SET enable_seqscan = off; SELECT count(*) AS seed_docs FROM iso_dir WHERE body @@> 'seed';
seed_docs
---------
      200
(1 row)

step s2r: RESET sift.test_fail_pages; SELECT sift.promote('iso_dir_idx') >= 0 AS promoted;
promoted
--------
t       
(1 row)

step s2m: SELECT sift.merge('iso_dir_idx') >= 0 AS merged; SELECT count(*) < 40 AS merged_down FROM sift.segments('iso_dir_idx');
merged
------
t     
(1 row)

merged_down
-----------
t          
(1 row)

step s1q: SET enable_seqscan = off; SELECT count(*) AS seed_docs FROM iso_dir WHERE body @@> 'seed';
seed_docs
---------
      200
(1 row)

step s1c: COMMIT;
step s3q: SELECT iso_agree('iso_dir', 'seed') AS agree_seed, iso_agree('iso_dir', 'room') AS agree_room, iso_verify('iso_dir_idx') AS verified;
agree_seed|agree_room|verified
----------+----------+--------
t         |t         |t       
(1 row)