include "_empty"

# (include (@ 1 0-7) ‘.../test-files/mds-kbdc/process-includes/valid/_empty’
#   (.inner nil)
# )
# .../test-files/mds-kbdc/process-includes/valid/_empty: warning: file is empty
# 
# .../test-files/mds-kbdc/process-includes/valid/include_empty_file:1:0–7: note: included from here
#  include "_empty"
#  ^^^^^^^