Consider a graph like this:
D |\ B C |/ A
drawdag will add a file called A in commit A, file B in B, file C in
C. That's fine and expected. In merge commits like D, I would expect
the files and their contents to be taken from the parent commits, so
commit D in this example would have files A, B, and C. However,
drawdag will instead add the file D compared to the first
parent. Depending on whether B or C got a smaller nodeid, the contents
of D would be {A, B, D} or {A, C, D}. This patch changes it to to be
{A, B, C}.