'man systemd.target' says:
Unless DefaultDependencies= is set to false, target units will
implicitly complement all configured dependencies of type
Wants=, Requires=, RequiresOverridable= with dependencies of type
After= if the units in question also have DefaultDependencies=true.
It did not work because of a forgotten negation.
/* If either side wants no automatic dependencies, then let's
* skip this */
if (!u->meta.default_dependencies ||
- target->meta.default_dependencies)
+ !target->meta.default_dependencies)
return 0;
/* Don't create loops */