If you migrate with /version -1, it migrates down, but all the way down taking -1 as a literal for call down all the way to 0.

I added functionality so that if you pass in -1, it moves to current issue minus 1. This is implemented as a literal look, so if you do -2, you get the previous behavior. Also if you want to move to 0, you should explicitly pass 0.

Patch attached.