gistfile1.txt

#!bash
if [ -n "$2" ]; then
    export SOURCE=$1 ;
    export DESTINATION=$2 ;
else
    export SOURCE=HEAD ;
    export DESTINATION=$1 ;
fi

export GIT_INDEX_FILE=`git rev-parse --show-toplevel`/.git/aux-merge-index ;
export GIT_WORK_TREE=`create_temporary_folder gm_`;
echo $GIT_INDEX_FILE
trap 'rm -f '"'$GIT_INDEX_FILE'"'; rm -rf '"'$GIT_WORK_TREE'" 0 1 2 3 15 ;
mkdir $GIT_WORK_TREE/.git
set -e ;
git read-tree -im `git merge-base $DESTINATION $SOURCE` $DESTINATION $SOURCE ;
#echo Finished read-tree
#sleep 1000
git merge-index git-merge-one-file -a
#echo Finished merge-index
git write-tree \
| xargs -i@ git commit-tree @ -p $DESTINATION -p $SOURCE -m "Merge $SOURCE into $DESTINATION" \
| xargs git update-ref -m"Merge $SOURCE into $DESTINATION" refs/heads/$DESTINATION ;
exit 0