[brechtm]

git-subtree duplicates history. First you make a regular commit containing both your main project's changes and the subtree changes. Afterwards the subtree change is merged in again (or "subtree split --rejoin" or "subtree merge").

The advantage of git-subrepo is that your changes are immediately split up between the main project and the subrepo. Eventually, you should also be able to supply a separate commit message for the subrepo change (see "random ideas" section in the article).