# eselect opengl [...] --use-old If an implementationis already set, use that one [...] Missing space between "impementation" and "is".
Just found out, that this typo is not in /usr/share/eselect/modules/opengl.eselect. Weird. Since I have a problem with eselect opengl anyway, I guess there is a problem on my box, such as an implementation overriding the real thing.