When we discard a page in a diagnostic build, we check that there are no hazard pointers to that page. Generally this is true, because we make sure there are no hazard pointers as part of locking a page for eviction. However, reading threads set a hazard pointer before checking the WT_REF_LOCKED flag, so there is a brief window when this assertion can fire.

The best idea I've had so far is to sleep and loop a few times, then print a warning message instead of making this an assertion failure.

e.g., http://mjc.homeunix.org:8180/job/wiredtiger-test-format-stress-santizer/1746/console