That doesn't work very well. Consider what happens if two different clones of a repo update the metadata last-known url at the same time with different urls. Me

That doesn't work very well. Consider what happens if two different clones of a repo update the metadata last-known url at the same time with different urls. Merge conflicts. This is why git-annex uses a separate branch for location tracking information, which it can merge in a conflict-free manner.