Graphical glitch during rockets/grenades explosion

Sometimes (not always), I notice a glitch when Mortar / Devastator rockets explode. See screenshot below.

It doesn't last very long, probably only a few frames.

Setup: Xonotic 0.8.2 on ArchLinux, with nVidia 378.13 drivers.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information