Then, I ran the same test as WT-635 on my Mac laptop and got a different error:
% ./wtperf -O ../../../bench/wtperf/runners/update-checkpoint-btree.wtperf -h ./WT_TEST
file:test.wt, session.checkpoint: the 1967 and 1969 keys on page at [write-check] are incorrectly sorted
Checkpoint failed. Error: WT_ERROR: non-specific WiredTiger error