* guix/import/utils.scm: (git-origin, git->origin): Add procedures.
* guix/import/elpa.scm
(download-git-repository): Remove function download-git-repository.
(git-repository->origin): Remove function git-repository->origin.
(ref): Add function ref.
(melpa-recipe->origin): Use functions git->origin and ref.
* guix/import/go.scm
(git-checkout-hash): Remove function git-checkout-hash.
(transform-version): Add function transform-version.
(vcs->origin): Use functions git->origin and transform-version. Add
optional argument transform-version.
* tests/import/go.scm
(go-module->guix-package): Adapt test case to changes in guix/import/go.scm.
* guix/import/luanti.scm
(download-git-repository): Remove function download-git-repository.
(make-luanti-sexp): Use function git->origin.
* tests/luanti.scm
(make-package-sexp): Refresh function accordingly.
* guix/import/composer.scm
(make-php-sexp): Use function git->origin.
Change-Id: Ied05a63bdd60fbafe26fbbb4e115ff6f0bb9db3c
Signed-off-by: Liliana Marie Prikler <liliana.prikler@gmail.com>