How do I get SaltStack to skip managing file for log.sh if it doesn't exist?

run.sh

#!/bin/sh
exec 2>&1
exec /opt/runit_enabled/bin/runnable.sh

runit_enabled.sls

# run.sh source exists and will be managed.
/etc/service/{{ sls }}/run:
  file.managed:
    - source: salt://{{ sls }}/run.sh
    - makedirs: True

#
# log.sh source does not exist and I would like to silently not manage it.
# How to do this?
#
/etc/service/{{ sls }}/log/run:
  file.managed:
    - source: salt://{{ sls }}/log.sh    
    - makedirs: True