There is a period of time after a mongobridge process starts up but before it is ready to accept connections. If a mongod server tries to connect to the mongobridge in this period, it will fail. This can be a problem, for example, when we restart a mongobridge and its associated mongod server in a replica set test. If we restart the mongobridge, and then restart the mongod, the mongod replica set node will try to identify itself by calling _isSelf against the mongobridge host. If the mongobridge is not ready to accept connections yet, then the command will fail, causing the node to consider itself removed from the replica set config. We should have some way to make sure the mongobridge is ready to accept connections in our tests.