In order to avoid interrupting ourselves due to our own stepdown, we use uninterruptible locks when writing lastVote in an election. Unfortunately if we've taken the global lock in X mode for FCBIS storage change, this leads to a deadlock – we're trying to acquire a write lock on an uninterruptible opCtx while also attempting to kill the opCtx so we can change storage and release the lock.

The quick fix might be to not acquire the uninterruptible lock guard during STARTUP2, but we should definitely add a test for this; since initial sync nodes are usually non-voting we don't have coverage for an election during it.