This is a followup to 8aeccc6240.
* guix/transformations.scm (package-with-upstream-version): New procedure.
(transform-package-latest)[package-with-latest-upstream]: Remove.
Use 'package-with-upstream-version' instead.
(transform-package-version): New procedure.
(%transformations, %transformation-options)
(show-transformation-options-help/detailed): Add '-with-version'.
* tests/transformations.scm ("options->transformation, with-version"):
New test.
* doc/guix.texi (Package Transformation Options): Document '--with-version'.
(Defining Package Variants): Mention it.