I'm not sure if this bug can be safely closed now, since I don't know if the behaviour I described previously was intended.
What has been resolved with the release of libgit2-glib/0.26.2-1 is that the 'Preferences' menu becomes available again in gitg, and you can choose the 'Show history in topological order' to restore the original behaviour in version 0.24. Best regards, Carlos
