Preserve file permissions

[mharacewiat]

Description

Fixes issues with file permissions on root directory when using paths with exclude directories.

Reproducer

Given a repository with foo folder to be splitted. It contains script.sh executable file.

git ls-tree -r --format='%(objectmode) - %(path)' split_origin | grep foo/script.sh
100755 - foo/script.sh

Experiment with splitting.

splitsh-lite \
    --prefix foo/ \
    --target refs/heads/split_target_simple \
    --origin refs/heads/split_origin

splitsh-lite \
    --commit XYZ \
    --prefix foo/ \
    --target refs/heads/split_target_simple_with_commit \
    --origin refs/heads/split_origin

splitsh-lite \
    --prefix foo/::not-important:also-not-important \
    --target refs/heads/split_target_with_excluded_folders \
    --origin refs/heads/split_origin

splitsh-lite \
    --commit XYZ \
    --prefix foo/::not-important:also-not-important \
    --target refs/heads/split_target_with_excluded_folders_and_commit \
    --origin refs/heads/split_origin

Validate.

git ls-tree -r --format='%(objectmode) - %(path)' split_target_simple | grep script.sh
100755 - script.sh

git ls-tree -r --format='%(objectmode) - %(path)' split_target_simple_with_commit | grep script.sh
100755 - script.sh

git ls-tree -r --format='%(objectmode) - %(path)' split_target_with_excluded_folders | grep script.sh
100644 - script.sh

git ls-tree -r --format='%(objectmode) - %(path)' split_target_with_excluded_folders_and_commit | grep script.sh
100644 - script.sh