Interoperability workshop - streamability problem with match pattern in Saxon

During this morning's workshop we found that Saxon reported this match pattern:

match="part[not(map:contains(accumulator-before('selected-part-ids'), @id))]"

as being not motionless, causing streaming of the containing stylesheet to fail.

I have confirmed that this match pattern should be motionless according to the spec, and that it was failing in Saxon 9.7 due to a bug, recorded here:

https://saxonica.plan.io/issues/2616

I have added the test case to the test suite as stream-201.

Michael Kay
Saxonica