Per TGT-35041 the current behavior is that Analytics doesn't really know what a "control" experience vs non control experience is. It's just an extra label in Analytics because of this Target doesn't send information about Control Experience and Analytics may choose to show any experience as Control. To mitigate this Analytics does provide the user with an option to change the Control Experience from UI.
The feature requested is to make all of this happen behind the scenes and have the correct experience show up in Analytics as the Control out of the box.
