async_rpc::getAllResponsesOrFirstErrorWithCancellation takes a vector of future-like types and returns a single future that is ready when all of the input futures are ready. To do so, it chains a callback to defined here to each input future, the last of which to run will emplace a value in a promise that readies the output-future of the entire function. However, the callback is chained via getAsync here, which means that if the input future-like types are ExecutureFuture, they may not run in the case of executor shutdown. This means the promise for the output-future will eventually be destroyed without providing a value to the future, resulting in a BrokenPromise error propogating out. 

This is very similar to SERVER-54735 and some other related bugs, and can probably be handled either in the same way, or simply by chaining the callback via unsafeToInlineFuture.