WT_SESSION.checkpoint: wt-000019.lsm: an unexpected checkpoint start

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#  RUN PARAMETERS
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abort=0
alter=0
auto_throttle=1
backups=0
bitcnt=7
bloom=0
bloom_bit_count=28
bloom_hash_count=16
bloom_oldest=0
cache=60
cache_minimum=20
checkpoints=on
checkpoint_log_size=165
checkpoint_wait=65
checksum=uncompressed
chunk_size=2
compaction=1
compression=zlib
data_extend=0
data_source=lsm
delete_pct=5
dictionary=0
direct_io=0
encryption=rotn-7
evict_max=1
file_type=row-store
firstfit=0
huffman_key=0
huffman_value=0
independent_thread_rng=1
in_memory=0
insert_pct=68
internal_key_truncation=1
internal_page_max=9
isolation=snapshot
key_gap=20
key_max=256
key_min=256
leaf_page_max=9
leak_memory=0
logging=0
logging_archive=0
logging_compression=none
logging_file_max=109418
logging_prealloc=1
long_running_txn=0
lsm_worker_threads=4
merge_max=13
mmap=1
modify_pct=14
ops=100000
prefix_compression=0
prefix_compression_min=4
quiet=1
read_pct=5
rebalance=1
repeat_data_pct=54
reverse=0
rows=100000
runs=1
salvage=1
split_pct=74
statistics=0
statistics_server=0
threads=20
timer=360
transaction_timestamps=1
transaction-frequency=29
truncate=0
value_max=1936
value_min=10
verify=1
wiredtiger_config=
write_pct=8
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