Yep, Git's semantics are seriously lacking (see also renames). In Reviewable, we work around this with heuristics: we use Change-Id if it happens to be availa

Yep, Git's semantics are seriously lacking (see also renames). In Reviewable, we work around this with heuristics: we use Change-Id if it happens to be available, and otherwise do best-effort loose lexical matching on the commit messages to match up pairs across a rebase. It works reasonably well in practice but it's a bunch of complex code that I'd rather not have to maintain...