In read_concern_snapshot_catalog_invalidation.js, there is code to wait for an operation to start. The test is racy because the test assumes that once waitForOp() has returned, the operation is hanging on a fail point. This is not necessarily true, and can cause the test to fail if the following happens:

1) The operation starts, but does not reach the fail point
2) waitForOp is run, and returns true
3) createIndexes is run
4) The operation reaches the fail point and preallocates a snapshot at a time that includes the new index, so the operation unexpectedly succeeds