Sidekick out of wall under ceiling, hits the ceiling during sidekick
 

As the title describes, a very specific movement bug. Some tests require you wallclimb into a masked tile, then sidekick out of it. If there's a ceiling directly above you, you hit the ceiling. The way to avoid it is to jump a couple of times inside the mask and then sidekick. Sidekicking after getting stuck always results in bumping your head halfway through the sidekick.

What part of this series of events is described as the bug? Obviously wallclimbing is a bug, but I assume that part you don't want to get rid of.
Assuming some part of the described behavior is undesirable, what would be the desired behavior?
Is this a vanilla bug, a plus bug, or both?
Is there an example .j2l? And, ideally, a .j2m?

Faw you can post these directly on GitHub now.