Can't delete legend on graph

[nbunker]

went to make a graph and for some reason I can't delete the legend. When I went to "X" out the label, it doesn't appear to have an "x."

This is what I see at first:

And then when I x-out that undefined part, I get this:

And then I'm stuck with the legend there.

[austinclemens]

not related to variable names, can be reproduced simply with data like:

x,y,z 1,2,a 3,4,a 5,6,b 7,8,b

Seems to be specific to concatenating two geoms into one key item

[austinclemens]

related to #162