If the bridge is enabled, the real connection to the server is stored in _unbridgedNodes:

        if (_useBridge) {
            this.nodes[n].connectToBridge();
            _unbridgedNodes[n] = conn;
        }

But when we restart a node, we don't take the bridge into account when looking for the existing options:

        if ((options && options.restart) || restart) {
            options = Object.merge(this.nodes[n].fullOptions, options);
        }

If _useBridge is true, then this.nodes[n].fullOptions will be undefined.

One symptom of the bug is that nodes that are restart when the bridge is enabled will not be restarted on their old port; instead, they'll be assigned a new port number.