Branch line colors

[vassilisw]

Branch lines change color, every time we expand or collapse merge commits, etc

e.g. as shown in the screenshot, when we expand the first merge commit the branch line beside it,
turns from purple to red (and back, if we collapse it again).

Preferred solution

I think that the branches that appear when when you expand a (merge) commit, etc,
should just get a new color (instead of all the lines updating their color every time!).
This way, it's easier to follow the hierarchy when updating the view by expanding/collapsing commits

Screenshots