Broken by commit: 9cd094bf8b12e1f3ea273de3c00e52d5bb294ee0

Stacktrace from test_hs01.py:
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007ffff7a24801 in __GI_abort () at abort.c:79
#2 0x00007ffff5105712 in __wt_abort (session=0xd4de60) at ../src/os_common/os_abort.c:30
#3 0x00007ffff4fffa7e in __wt_txn_begin (session=0xd4de60, cfg=0x0) at ../src/include/txn.i:881
#4 0x00007ffff4fffbd5 in __wt_txn_autocommit_check (session=0xd4de60) at ../src/include/txn.i:922
#5 0x00007ffff5001e59 in _wt_page_in_func (session=0xd4de60, ref=0xc90f10, flags=1040, func=0x7ffff51a5db0 <func.35390> "_wt_row_search", line=425) at ../src/btree/bt_read.c:415
#6 0x00007ffff5041519 in _wt_page_swap_func (session=0xd4de60, held=0xd99198, want=0xc90f10, flags=1024, func=0x7ffff51a5db0 <func.35390> "_wt_row_search", line=425) at ../src/include/btree.i:1695
#7 0x00007ffff5042b9e in __wt_row_search (cbt=0x122f690, srch_key=0x122f790, insert=true, leaf=0x0, leaf_safe=false, leaf_foundp=0x0) at ../src/btree/row_srch.c:425
#8 0x00007ffff4fda4ee in __cursor_row_search (cbt=0x122f690, insert=true, leaf=0x0, leaf_foundp=0x0) at ../src/btree/bt_cursor.c:414
#9 0x00007ffff4fdcb25 in __btcur_update (cbt=0x122f690, value=0x122f7b8, modify_type=4) at ../src/btree/bt_cursor.c:1302
#10 0x00007ffff4fdd810 in __wt_btcur_update (cbt=0x122f690) at ../src/btree/bt_cursor.c:1580
#11 0x00007ffff5082d8d in __curfile_update (cursor=0x122f690) at ../src/cursor/cur_file.c:366
#12 0x00007ffff50cbaef in __hs_insert_record (session=0xd4de60, cursor=0x122f690, btree_id=2, key=0x122efd0, upd=0xf93480, type=4 '\004', hs_value=0xd1e8c0, stop_ts_pair=...) at ../src/history/hs.c:362
#13 0x00007ffff50cc4f8 in __wt_hs_insert_updates (cursor=0x122f690, btree=0xddf620, r=0x13e4cf0, multi=0x1499ee0) at ../src/history/hs.c:605
#14 0x00007ffff5139db0 in __rec_hs_wrapup (session=0xd4de60, r=0x13e4cf0) at ../src/reconcile/rec_write.c:2296
#15 0x00007ffff513958b in __rec_write_wrapup (session=0xd4de60, r=0x13e4cf0, page=0xf93750) at ../src/reconcile/rec_write.c:2132
#16 0x00007ffff5134c8b in __reconcile (session=0xd4de60, ref=0x10692a0, salvage=0x0, flags=86, page_lockedp=0x7fffffffbffe) at ../src/reconcile/rec_write.c:200
#17 0x00007ffff513487d in __wt_reconcile (session=0xd4de60, ref=0x10692a0, salvage=0x0, flags=86) at ../src/reconcile/rec_write.c:87
#18 0x00007ffff50c77a9 in __evict_review (session=0xd4de60, ref=0x10692a0, evict_flags=4, inmem_splitp=0x7fffffffc0df) at ../src/evict/evict_page.c:630
#19 0x00007ffff50c5dba in __wt_evict (session=0xd4de60, ref=0x10692a0, previous_state=3, flags=4) at ../src/evict/evict_page.c:149
#20 0x00007ffff50c5bdc in __wt_page_release_evict (session=0xd4de60, ref=0x10692a0, flags=0) at ../src/evict/evict_page.c:80
#21 0x00007ffff5001d32 in _wt_page_in_func (session=0xd4de60, ref=0x10692a0, flags=1024, func=0x7ffff51a5db0 <func.35390> "_wt_row_search", line=425) at ../src/btree/bt_read.c:363
#22 0x00007ffff5041519 in _wt_page_swap_func (session=0xd4de60, held=0xddf738, want=0x10692a0, flags=1024, func=0x7ffff51a5db0 <func.35390> "_wt_row_search", line=425) at ../src/include/btree.i:1695
#23 0x00007ffff5042b9e in __wt_row_search (cbt=0xded9d0, srch_key=0xdedad0, insert=true, leaf=0x0, leaf_safe=false, leaf_foundp=0x0) at ../src/btree/row_srch.c:425
#24 0x00007ffff4fda4ee in __cursor_row_search (cbt=0xded9d0, insert=true, leaf=0x0, leaf_foundp=0x0) at ../src/btree/bt_cursor.c:414
#25 0x00007ffff4fdcb25 in __btcur_update (cbt=0xded9d0, value=0xdedaf8, modify_type=4) at ../src/btree/bt_cursor.c:1302
#26 0x00007ffff4fdd810 in __wt_btcur_update (cbt=0xded9d0) at ../src/btree/bt_cursor.c:1580
#27 0x00007ffff5082d8d in __curfile_update (cursor=0xded9d0) at ../src/cursor/cur_file.c:366
#28 0x00007ffff5422bb0 in _wrap_Cursor_update (self=<optimized out>, args=<optimized out>) at wiredtiger_wrap.c:4451
#29 0x0000000000566ea1 in _PyCFunction_FastCallDict ()