Linus Torvalds [off-list ref] writes:
Maybe it's not a new thing, and it's just that the recent pattern of
merges in the git tree makes any version of gitk do horrible things.
It is both, but new gitk plays a major part of it.
There are too wide horizontal lines when many merges are
involved. My "next" branch from yesterday (which is essentially
what my "master" branch today) was somewhat more pleasant to
read with older gitk, but only somewhat.