Boost compilation does not understand block comment in JAM file

Question

I compile boost v1.72 from https://dl.bintray.com/boostorg/release/1_72_0/source

Ubuntu 18.04.4 LTS

gcc : 7.5.0

It compiles with error:

boost_1_72_0/tools/build/src/tools/types/sass-type.jam:8: in load
ERROR: rule "Copyright" unknown in module "sass-type".

My sass-type.jam file starts with:

#|
Copyright 2017 Dmitry Arkhipov
Distributed under the Boost Software License, Version 1.0. (See
accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
|#

import scanner ;
import type ;
...

If I replace block comment #| .. |# by a comment # on each line, it compiles. Why my boost compilation does not recognize block comment?

Thanks,