I don't want to bike shed, but the prevalence of empty merge commits in
the repo seems both undesirable and avoidable. I always rebase my work
instead of merge. Is there a reason this is not standard practice in the
repo? It certainly makes for a nicer history.

When we switched we didn't want to affect people's current workflow too much (i.e. they already had to learn git so we kept rebasing out of it at the beginning.)

-- Johan