Graphics.Graph.graph() doesn't set legend colors.
Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=4059
Reported by Adam Montague, Sirius Hosting firstname.lastname@example.org
When creating a graph with Graphics.Graph.pie() or bar(), if you set legend_texts to something, then a legend will be created with appropriately colored boxes. If you do the same with Graphics.Graph.graph(), then the little boxes in the legend are all white.