MavenProjectTest.testDeleteSetBuildDeletesModuleBuilds used to fail in some environments because it was using the default local repository, and a build of one submodule in isolation failed to find the installed snapshot artifact of its reactor dependency. Using PerExecutorLocalRepositoryLocator sometimes works, but only if the same executor runs both builds. PerJobLocalRepositoryLocator looks like it should work, but does not because when running the individual module build it uses a different repository from the module set build.

You would expect that in an aggregator project where modules have snapshot interdependencies, if you have built the whole module set then you should also be able to rerun a single module build and that it should find the dependency artifacts in the workspace, using a repository at top level.