Problem displaying merges when multiple branches are involved

[stronk7]

To reproduce:

• Create new git repo, add 1 file to it and commit.
• Create 2 branches (branch1 and branch2).
• Perform some modifications in branch1 and branch2 and commit
• Modify master and commit
• Merge master changes both to branch1 and branch2
• Modify master again
• Merge master again, first to branch1 and later to branch2

Expected result: both branch1 and branch2 should look practically the same (their dots and lines graph in the subject column), being 2 vertical lines with some lines representing the merges.

Current result: the last merged branch looks horrible, getting more and more complex (vertical lines) if the number of merges grown. And note it always seems to happen to the last merged branch. No matter if you quit and open gitx or whatever, the garbled visualization always applies to the last merged branch.

Note: the visualization problem doesn't seem to affect the upstream version, so it seems to be something introduced by this fork.