The official documentation doesn't say anything, so I can't confirm it. I seem to remember some posts where they talked about the problems with bundles and I seem to remember the same thing happening with sales.
It doesn't make any sense to me to put a free game on sale, but with so many developers, there are always people who will do what no one else expects.
In any case, remember that it is possible to put a preview per file on projects that are paid. For example, you sell the game for 10, but if someone pays 12, they could download the music or an art book, etc.