Comment 0 for bug 1837254

In parallel builds where a list of image targets are provided the build
may produce binaries that are not part of the named set of targets but
are created by series dependencies. These implicitly created binaries
may be generated by multiple builds but are unused as our convention for
the ubuntu-cpc project is to only consume binaries from the explicitly
named image targets; this avoid overwriting the same object by multiple
parallel builds.