This is sensitive to the design of the delta format though, once you have merges. I had to write some code to migrate version history from Rational Team Concert

This is sensitive to the design of the delta format though, once you have merges. I had to write some code to migrate version history from Rational Team Concert to git. RTC has a uuid for each version of a file, and deltas are a set of zero or more predecessor versions, and a successor version. This allowed the same delta to be present in different “streams” (branches), if they only differed in files not relevant to the delta; but it becomes impossible to reconstruct a history of snapshots from the change sets.