Neat bug, you should report it
There are some "practical" applications actually. You can use this to get monsters that are following you to skip problematic levels (such as D:48/49 or the elemental temples).
Setup on the level you want to skip would be something like this:
Code:
++X ++@
+<+ --> +X+
+++ +++
With the X representing either a second monster following you down the stairs, or a paralyzed friendly monster. Abusing this to get Gaab'Baay past the air and earth temples would allow you to do an ultra paragon run on the current version.