OpamRepositoryPath.RemoteUrl constructor for parts of remote repositories, when applicable (http and rsync). Function take the repo's root url.
val repo : OpamTypes.url -> OpamTypes.urlRemote repo file
val packages_url : OpamTypes.url -> OpamTypes.urlRemote package files: $remote/packages
val archive : OpamTypes.url -> OpamTypes.package -> OpamTypes.urlRemote archive $remote/archives/$NAME.$VERSION.tar.gz