Revert "guix: git: Add new module."

This reverts commit a70b784708fb5e1b78430aa793d89ca04bc641a8.

Commit a70b784708f caused `guix pull` to fail:

ERROR: In procedure scm-error:
ERROR: no code for module (git)

1 files changed, 0 insertions, 123 deletions

diff --git a/guix/git.scm b/guix/git.scm
deleted file mode 100644
index 17a6784aef..0000000000
--- a/guix/git.scm
+++ /dev/null
@@ -1,123 +0,0 @@
-;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
-;;;
-;;; This file is part of GNU Guix.
-;;;
-;;; GNU Guix is free software; you can redistribute it and/or modify it
-;;; under the terms of the GNU General Public License as published by
-;;; the Free Software Foundation; either version 3 of the License, or (at
-;;; your option) any later version.
-;;;
-;;; GNU Guix is distributed in the hope that it will be useful, but
-;;; WITHOUT ANY WARRANTY; without even the implied warranty of
-;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;;; GNU General Public License for more details.
-;;;
-;;; You should have received a copy of the GNU General Public License
-;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
-
-(define-module (guix git)
-  #:use-module (git)
-  #:use-module (git object)
-  #:use-module (guix base32)
-  #:use-module (guix hash)
-  #:use-module (guix build utils)
-  #:use-module (guix store)
-  #:use-module (guix utils)
-  #:use-module (rnrs bytevectors)
-  #:use-module (ice-9 match)
-  #:use-module (srfi srfi-1)
-  #:export (%repository-cache-directory
-            latest-repository-commit))
-
-(define %repository-cache-directory
-  (make-parameter "/var/cache/guix/checkouts"))
-
-(define-syntax-rule (with-libgit2 thunk ...)
-  (dynamic-wind
-    (lambda ()
-      (libgit2-init!))
-    (lambda ()
-      thunk ...)
-    (lambda ()
-      (libgit2-shutdown))))
-
-(define* (url-cache-directory url
-                              #:optional (cache-directory
-                                          (%repository-cache-directory)))
-  "Return the directory associated to URL in %repository-cache-directory."
-  (string-append
-   cache-directory "/"
-   (bytevector->base32-string (sha256 (string->utf8 url)))))
-
-(define (clone* url directory)
-  "Clone git repository at URL into DIRECTORY.  Upon failure,
-make sure no empty directory is left behind."
-  (with-throw-handler #t
-    (lambda ()
-      (mkdir-p directory)
-      (clone url directory))
-    (lambda _
-      (false-if-exception (rmdir directory)))))
-
-(define (repository->head-sha1 repo)
-  "Return the sha1 of the HEAD commit in REPOSITORY as a string."
-  (let ((oid (reference-target (repository-head repo))))
-    (oid->string (commit-id (commit-lookup repo oid)))))
-
-(define (url+commit->name url sha1)
-  "Return the string \"<REPO-NAME>-<SHA1:7>\" where REPO-NAME is the name of
-the git repository, extracted from URL and SHA1:7 the seven first digits
-of SHA1 string."
-  (string-append
-   (string-replace-substring
-    (last (string-split url #\/)) ".git" "")
-   "-" (string-take sha1 7)))
-
-(define* (copy-to-store store cache-directory #:key url repository)
-  "Copy items in cache-directory to store.  URL and REPOSITORY are used
-to forge store directory name."
-  (let* ((commit (repository->head-sha1 repository))
-         (name   (url+commit->name url commit)))
-    (values (add-to-store store name #t "sha256" cache-directory) commit)))
-
-(define (switch-to-ref repository ref)
-  "Switch to REPOSITORY's branch, commit or tag specified by REF."
-  (let* ((oid (match ref
-                (('branch . branch)
-                 (reference-target
-                  (branch-lookup repository branch BRANCH-REMOTE)))
-                (('commit . commit)
-                 (string->oid commit))
-                (('tag    . tag)
-                 (reference-name->oid repository
-                                      (string-append "refs/tags/" tag)))))
-         (obj (object-lookup repository oid)))
-    (reset repository obj RESET_HARD)))
-
-(define* (latest-repository-commit store url
-                                   #:key
-                                   (cache-directory
-                                    (%repository-cache-directory))
-                                   (ref '(branch . "origin/master")))
-  "Return two values: the content of the git repository at URL copied into a
-store directory and the sha1 of the top level commit in this directory.  The
-reference to be checkout, once the repository is fetched, is specified by REF.
-REF is pair whose key is [branch | commit | tag] and value the associated
-data, respectively [<branch name> | <sha1> | <tag name>].
-
-Git repositories are kept in the cache directory specified by
-%repository-cache-directory parameter."
-  (with-libgit2
-   (let* ((cache-dir     (url-cache-directory url cache-directory))
-          (cache-exists? (openable-repository? cache-dir))
-          (repository    (if cache-exists?
-                             (repository-open cache-dir)
-                             (clone* url cache-dir))))
-     ;; Only fetch remote if it has not been cloned just before.
-     (when cache-exists?
-       (remote-fetch (remote-lookup repository "origin")))
-     (switch-to-ref repository ref)
-     (copy-to-store store cache-dir
-                    #:url url
-                    #:repository repository))))