function copy_revision {
  if [ -d "$1" ] && [ -d "$2" ]; then    
    pushd "$1" > /dev/null
    COMMIT="$(git rev-parse HEAD)"
    echo Switching "$(basename "$2")" to $COMMIT
    popd > /dev/null

    pushd "$2"
    git checkout "$COMMIT"
    popd > /dev/null
  else
    echo "Usage: copy_revision <git-dir-1> <git-dir-2>"
  fi
}