This has never worked for built/found programs, only for script files.
In commit 2fabd4c7dc scripts learned an
attribute stating which subproject they came from. In commit
3990754bf5 dist scripts learned to run
even from a subproject, and relied on that attribute to know when, in
fact, they came from a subproject.
Unfortunately the original attribute was only set in one half of an
if/else, and the other half returned early with only part of the work
done.
Fixes#9964