Fix expansion of empty lists in list context

When we are expanding a list in a list evaluation context, and the
list is empty, we'd rather generate no records at all. Previous
behaviour would simply have left the $IDENTIFIER in place unchanged.
4 jobs for master in 1 minute and 28 seconds
Status Job ID Name Coverage
  Test
passed #9090
run_tests

00:00:28

 
  Build Src
passed #9091
build:src

00:00:13

 
  Build Pkg
passed #9092
build:pkg

00:00:21

 
  Upload
passed #9093
upload:pkg

00:00:23