Possible bug? - trivial map with strange annoying behavior

[The Purple Panzer]

I've extracted a very small fragment of a map I'm working on - there are four mesh boxes touching to form a shaft. They all start at the same Z value, and all have the same height - yet when I'm driving around the top, I get stuck on some of the seams, as if there is a height discrepancy.

If you want to see this behavior, start bzfs with the map (I've included my Windows .bat file, which you might have to edit slightly), grab a Wings flag (which are under the shaft, or you can do as admin by doing
/flag give #0 WG
then fly to the top, and drive around. You'll stick when heading from what must seem like the server to be the lower block to the higher block, but not in the other direction.

This is so simple, and yet so weird, that I can't imagine what it might be. It could be that I'm just so tired I'm not seeing something obvious; but if not, maybe there's a bug somewhere in the code. I can see no reason why I can't drive across a flat boundary! (And indeed if this is a problem I think it might limit mapmaking a bit).

The server and client are both BZFlag 2.0.10.

Any hints, insight, etc. would be most appreciated. I dearly hope it's something I'm just not seeing.

[Triumph of the Soul]

This is indeed a bug which I also have been troubled by in the past. There is no fix that I know of, although in 2.0.9+, regular boxes can be given materials as well as mesh boxes. If you do this, the problem goes away, and the textures come out more nicely anyway.