The PCT updates the dependencies and test dependencies but it does not update the dependency management section of the pom file.
Now consider a situation where a plugin `a` uses some test utilities from another plugin `b` but it does not have a direct dependency on `b`. To do that `a` can use a `test` scoped dependency of `b` `tests` artifact. In those circumstances, it makes sense for `a` to use a dependency management section to be sure that `b` version (transitively added by `b` tests artifact to the test classpath) is deterministic and under control.
Problem is that PCT does not update dependencyManagement so in this cases the final version of `b` in the test classpath is different from the version of `b` tests utilities used