I have come back to this and added my vote, especially as i wished this was possible multiple times now 
This was such an integral part of song/pattern management on the Amiga back in the days (Protracker in my case). I would love to see this at some point.
I’ll add some food for thought and add two excellent videos explaining how this used to work on the Amiga:
And let’s not forget the Patternloop Command E6 (video is timestamped accordingly):
The combo of those 3 commands was extremely powerful and has created some of the most oustanding creations in tracker history.
Btw, i can recommend all of those videos from that channel to tracker enthusiasts.