Commit a1e26ca6 broke the `make-pom` & `pom-advanced` dependency-management
tests by replacing one reference to `IBiblioResolver.DEFAULT_M2_ROOT` in
`Resolver`, but not the other reference in `MakePom`:
https://travis-ci.org/sbt/sbt/jobs/31939788#L2517-L2519
...the secure url was no longer recognised as the default Maven Repository
root, so was erroneously exported.