Max Bolingbroke:
Then, adding complexity, git branches are normally done by switching in-place. So how does this interact with VCS like darcs that doesn't have a concept of in-place switching of branches?
Since we will set up Git to ignore the contents of the Darcs repos, it will simply leave them unmodified. This is exactly like the current situation, where rolling back / patching the GHC repo does not affect the others. If you want Darcs-like behaviour (one branch per repo) you are free to do this in Git as well, in which case since you never switch branches the nested Darcs repos should never be inappropriate for your branch.
This ignores that the ability to have branches, switch between them, and merge has been cited as one of the reasons for switching to git. Embedded darcs library repos would hence nullify, or at least reduce, one of the advantages. Manuel