def check_copy_from_header(req):
    return check_path_header(req, 'X-Copy-From', 2,
                             'X-Copy-From header must be of the form '
                             '<container name>/<object name>')
Validate that the value from x-copy-from header is
dataset/ETHPy150Open openstack/swift/swift/common/constraints.py/check_copy_from_header