When archival is enabled for a test or test suite, resmoke.py sends a SIGABRT signal to its fixture processes to take a core dump of them (in addition to collecting the mongod data files). If a JavaScript test has already invoked the hang analyzer via an assert.soon(), then the core file generated from the hang analyzer will be overwritten.

[fsm_workload_test:agg_merge_when_matched_replace_with_new] 2020-05-26T08:34:20.234+0000 sh118695| Saved corefile dump_mongod.4235.core
...
[ShardedClusterFixture:job0:shard0:secondary0] Attempting to send SIGABRT from resmoke to mongod on port 20002 with pid 4235...

Note that the core dump taken by resmoke.py sending a SIGABRT signal is unlikely to match the thread stacks in the hang analyzer output because running the hang analyzer is expected to perturb the state of the MongoDB cluster.