test/format failure: NULL btree->root_page reference with LSM

############################################

#  RUN PARAMETERS

############################################

# bitcnt not applicable to this run

cache=94

compression=none

data_extend=0

data_source=lsm

delete_pct=14

dictionary=0

file_type=row-store

huffman_key=0

huffman_value=0

insert_pct=40

internal_key_truncation=0

internal_page_max=14

key_gap=4

key_max=102

key_min=27

leaf_page_max=21

ops=382656

prefix=1

repeat_data_pct=37

reverse=0

rows=600

runs=0

split_pct=65

threads=10

value_max=1024

value_min=3

# wiredtiger_config not applicable to this run

write_pct=5

(gdb) where

#0  0x00000000004a0f7b in __wt_row_search (session=0x8024a5ad0, 

    cbt=0x805620300) at ../src/btree/row_srch.c:139

WT-1  0x0000000000493773 in __wt_btcur_insert (cbt=0x805620300)

    at ../src/btree/bt_cursor.c:314

WT-2  0x0000000000460f2f in __curfile_insert (cursor=0x805620300)

    at ../src/cursor/cur_file.c:223

WT-3  0x00000000004754ad in __clsm_put (session=0x8024a5ad0, clsm=0x806007300, 

    key=0x8060073b8, value=0x8060073d8, position=0)

    at ../src/lsm/lsm_cursor.c:996

WT-4  0x000000000047516f in __clsm_insert (cursor=0x806007300)

    at ../src/lsm/lsm_cursor.c:1083

WT-5  0x0000000000407228 in row_insert (cursor=0x806007300, key=0x7ffffe5f2f30, 

    value=0x7ffffe5f2f10, keyno=511) at ../../../test/format/ops.c:881

WT-6  0x0000000000405df7 in ops (arg=0x80240ea30)

    at ../../../test/format/ops.c:321

(gdb) p btree

$1 = (WT_BTREE *) 0x804eee100

(gdb) p btree->root_page

$2 = (WT_PAGE *) 0x0

(gdb) p session->dhandle->name

$7 = 0x804fab340 "file:wt-000004.lsm"

t, file:wt-000013.lsm, session.checkpoint: discarded page has hazard pointer: (0x807f93d00: ../src/btree/row_srch.c, line 220)

t, file:wt-000013.lsm, cursor.search: ../src/btree/bt_page.c, 77: page != NULL && !WT_PAGE_IS_ROOT(page)

t, file:wt-000013.lsm, cursor.search: aborting WiredTiger library