This never generated an error locally because the directories happen to exist.
Empty directories are generally not stored in git and so when unit tests were run on Github the missing directory problem becomes exposed.
This is not a bug because the related bug is fixed in commit
ecddd4d16504d3e2d9502d6a4dfe67658dce98dc.
This only silences the newly added warning.
build_sources_headers status_string.h
-build_sources_documentation man
+build_sources_documentation
build_script yes
build_shared yes
build_sources_headers type.h
-build_sources_documentation man
+build_sources_documentation
build_script yes
build_shared yes
build_sources_headers execute.h execute/common.h
-build_sources_documentation man
+build_sources_documentation
build_script yes
build_shared yes