[[!comment format=mdwn
 username="joey"
 subject="""comment 1"""
 date="2019-03-06T19:35:16Z"
 content="""
In a way the problem is that schrootProps uses toChildProperty,
which bypasses Propellor's type-level OS system.

I think it may be possible to move the use of Apt.stdSourcesList
out of Sbuild.built', and have the user pass those properties into it,
along with the OS property and their other desired properties, 
and let propellor type check that the properties passed to it all work
together.
"""]]
