this is correct, but it's getting a bit hard to read :)

How about extracting a `_wasUnmerged` function to get us something like
```
    if (this.call.group) {
      CallScreen.moveToGroup(this.node);
      this._leftGroup = false;
    } else if (this._wasUnmerged()) {
      CallScreen.insertCall(this.node);
      this._leftGroup = false;
    } else {
      this._leftGroup = !isHangingUpAll;
    }

```
what do you think?