Bug report: OS X git-merge deletes recapitalized files when rename detection fails

[Dan Fabulich <dan@fabulich.com>]

On case-insensitive filesystems, git-merge deletes files that were recapitalized in another branch if rename detection fails.

To repro: Run this script with git 1.8.4 on a case-insensitive filesystem. It repros for me on the default HFS filesystem on OS X 10.8, and also on Win7 NTFS.

#!/bin/sh -x
# create git repo
git --version
rm -rf caps
git init caps
cd caps
git config --get core.ignorecase
# commit empty file called "file"
echo file > file
git add .
git commit -am "initial commit"
# create branch called "branch"
git branch branch
# rename "file" to "File"
# using --force per http://stackoverflow.com/questions/6899582
git mv --force file File
echo "completely different content" > File
git commit -am "renamed to File"
# switch to branch, make a non-conflicting commit
git checkout branch
echo newfile > newfile
git add .
git commit -am "branch commit"
# merge master into branch, commit merge
git merge --verbose --commit --no-edit master
ls File
git status

Actual: At the end of the script, the renamed File has been deleted by git-merge. "ls: File: No such file or directory" According to git-status, the deletion is not yet staged.

Expected: There should be no untracked changes at the end of this script. The script runs as expected on Linux or case-sensitive HFS.

-Dan Fabulich

P.S. On case-insensitive HFS, git-init will automatically set core.ignorecase to true. For the sake of the experiment, I also tried setting core.ignorecase to false in the test repository.

When I did that, I was unable to even checkout the "branch" branch without using --force. ("The following untracked working tree files would be overwritten by checkout: file" But git-status reported no untracked changes.)

And then, once I did use force to switch to the branch, I was unable to merge from master at all. ("The following untracked working tree files would be overwritten by merge: File" But again, git-status reported no untracked changes.)