Jeff King [off-list ref] writes:
So perhaps we could do something better on the viewing side, and
"simplify" combined merges for files with all-identical parents.
Or you can ask to show the difference with the first parent, no?
I do not think giving a single-parent diff when --cc/-c is asked
for, which is a clear indication that the caller is aware that the
commit in question is a merge, is such a good idea.