I don't think something should work, but only work some of the time, to me that's a bug. As a fix, it would be nice if multiple variable support was disabled when no equal sign preceeds /var %var.
I wouldn't complain about this if /set and /var had the same syntax. I personally like it better without an equal sign, and could care less about multiple variables in a single /var (I'd probably feel differently if there were variable types).
As demonstrated by qwerty in that thread, you don't need to be
setting multiple variables for the command to break when not
using =. Maybe it should just show error, but I ask, why not
just use the proper syntax? It seems to work perfectly when
used properly, go figure.