When you try to rebase, especially with rebase --preserve, a whole lot of bad things happen due to the trees not being very similar.
For instance, if both sides have a README.mkdn, well, this happens:
git rebase --preserve repick
CONFLICT (add/add): Merge conflict in README.mkdn
Automatic merge failed; fix conflicts and then commit the result.
Error redoing merge 13ad9ead2785efe6f2b6b00e39349749f8382bce
Even though their final paths are different, merge preservation means the magic merge commits are discarded and re-attempted, and they're re-attempted without the path transformation! Ugh! :/
Git subtree has the same defect and its infuriating to work around.
( Problem happens without merge preservation too :( )
Is this still a problem?
We no longer have magic merges.
This looks much improved now.