Re: A rebase regression in Git 2.18.0

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Tue, Aug 28 2018, Nikolay Kasyanov wrote:

> Hi,
>
> I’ve found something that may be a regression in git rebase implementation in 2.18.0.
> First I spotted it on macOS but I can also confirm it happening on Linux.
> Git 2.19.0.rc0.48.gb9dfa238d is affected too.
>
> In order to trigger it, a repo layout similar to the following is required:
>
> files/
> 	file1
> 	file2
> 	file3
> 	file4
> 	file5
> project
>
> Let’s call this state baseline. Then, in a branch, let’s edit project file and move file3 to nested/files subdirectory, here’s the final layout:
>
> files/
> 	file1
> 	file2
> 	file4
> 	file5
> nested/
> 	files/
> 		file3
> project
>
> Let’s get back to master and also edit project file to cause a conflict. After that trying to rebase the branch upon master will cause the following git status output:
>
> rebase in progress; onto baf8d2a
> You are currently rebasing branch 'branch' on 'baf8d2a'.
>   (fix conflicts and then run "git rebase --continue")
>   (use "git rebase --skip" to skip this patch)
>   (use "git rebase --abort" to check out the original branch)
>
> Changes to be committed:
>   (use "git reset HEAD <file>..." to unstage)
>
> 	renamed:    files/file1 -> nested/files/file1
> 	renamed:    files/file2 -> nested/files/file2
> 	renamed:    files/file3 -> nested/files/file3
> 	renamed:    files/file4 -> nested/files/file4
> 	renamed:    files/file5 -> nested/files/file5
>
> Unmerged paths:
>   (use "git reset HEAD <file>..." to unstage)
>   (use "git add <file>..." to mark resolution)
>
> 	both modified:   project
>
> All renames except file3 are invalid and shouldn’t be here.
> Here’s how the output looks like produced by an older Git version (git version 2.15.1):
>
> rebase in progress; onto baf8d2a
> You are currently rebasing branch 'branch' on 'baf8d2a'.
>   (fix conflicts and then run "git rebase --continue")
>   (use "git rebase --skip" to skip this patch)
>   (use "git rebase --abort" to check out the original branch)
>
> Changes to be committed:
>   (use "git reset HEAD <file>..." to unstage)
>
> 	renamed:    files/file3 -> nested/files/file3
>
> Unmerged paths:
>   (use "git reset HEAD <file>..." to unstage)
>   (use "git add <file>..." to mark resolution)
>
> 	both modified:   project
>
> Here’s a ready-to-use repository: https://github.com/nikolaykasyanov/git-rebase-bug.

Thanks for the test case. This bisects down to 9c0743fe1e
("merge-recursive: apply necessary modifications for directory renames",
2018-04-19) first released as part of 2.18.0.

I have not dug to see if the behavior change is desired or not, that
commit changed the results of a bunch of test cases, maybe it was
intended. Elijah?