Error when "git mv" file in a sparsed checkout

Hello,

I have used the procedure described below for many years. In fact, this procedure is part of a script which I am using for about 10 years. This procedure was definitely working with git-2-25-1 and git-2.26.2.

Now, with git-2.34.1 (on a freshly installed ubuntu-22.04), this procedure fails.

Here is what I do:

I want to rename a file on a branch which is not currently checked out without messing/touching my current working directory.

For this, I first create a clone of the repo with shared git-directory:

  $ SANDBOX=/var/tmp/manage-scans-X1pKZQiey
  $ WT=$SANDBOX/wt
  $ GIT=$SANDBOX/git

  $ mkdir -p $SANDBOX
  $ git --work-tree $WT --git-dir $GIT clone -qns -n ~/upstream-repo $GIT

Then, I do a sparse checkout in this clone, containing only the file that is to be renamed:

  $ cd $WT
  $ echo 'path/to/old-filename' >>$GIT/info/sparse-checkout
  $ git --work-tree $WT --git-dir $GIT config core.sparsecheckout true
  $ git --work-tree $WT --git-dir $GIT checkout -b the-branch remotes/origin/the-branch
  Switched to a new branch 'the-branch'

Next step would be to "git mv" the file:

  $ mkdir -p /path/to  # already exists, but should do no harm
  $ git --work-tree $WT --git-dir $GIT mv path/to/old-filename path/to/new-filename
  The following paths and/or pathspecs matched paths that exist
  outside of your sparse-checkout definition, so will not be
  updated in the index:
  path/to/new-filename
  hint: If you intend to update such entries, try one of the following:
  hint: * Use the --sparse option.
  hint: * Disable or modify the sparsity rules.
  hint: Disable this message with "git config advice.updateSparsePath false"

This error is something I have not expected.

Error message suggests, there already exists a file named "new-filename". This is not true at all. There is no file named "new-filename" in the entire repository. Not in any directory of any branch.