Author Coloring setting
The description of this setting says
Color changesets by author name. If not enabled, the changes are colored green for merge, red for non-trivial parents, black for normal. Default: False
If enabled, the changesets will be colored by author name as stated. However, if set to false/default, all changeset will be black - no matter if they are merge changesets or not.
If the coloring is wrong or the description is wrong, I don't know.