https://jira.mongodb.org/browse/SERVER-100158 has introduced potential dead lock:

In this test there are three relevant threads: (1) the parent JS test shell, (2) the parallel JS test shell and (3) the range deleter.

Based on the stack dumps we have (more details can be found in https://jira.mongodb.org/browse/BF-36871):

The parallel JS test shell is sitting waiting on a failpoint, within the update stage while holding an IX lock. The failpoint can only be unblocked by the parent JS test shell.