While the backtrace itself won't be particular helpful in debugging the failure (as the stack has already been unwound) it will make it so the automated tooling to extract relevant log messages can find the uncaught exception message. The only log message that appears is the following:

[ReplicaSetFixture:job0:secondary2] 2018-05-20T12:58:19.763+0000 E NETWORK  [conn118] Uncaught std::exception: basic_string::_M_create, terminating

https://logkeeper.mongodb.org/lobster/build/7b9af1499f010b4d302f9f2e2ec3ebba/all?f=10ReplicaSetFixture%3Ajob0%3Asecondary2&bookmarks=0%2C938783

We could likely instead just call std::terminate() inside the catch-block as myTerminate() already logs details about the exception as well as a backtrace of where it was caught.