gnu: emacs-beginend: Don't use unstable tarball.

* gnu/packages/emacs-xyz.scm (emacs-beginend)[source]: Use GIT-FETCH and
GIT-FILE-NAME.

gnu/packages/emacs-xyz.scm

@@ -10066,13 +10066,13 @@ until the top-level form is no longer a macro call.")
     (version "2.0.0")
     (source
      (origin
-       (method url-fetch)
-       (uri (string-append "https://github.com/DamienCassou/beginend/archive/"
-                           "v" version ".tar.gz"))
-       (file-name (string-append name "-" version ".tar.gz"))
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/DamienCassou/beginend.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
        (sha256
-        (base32
-         "0z4rbwffh9vxfvcrlvym4p73z7gf72q0b5iv33llbpcpbijknnrq"))))
+        (base32 "1jbhg73g1rrkbwql5vi2b0ys9avfazmwzwgd90gkzwavw0ch9cvl"))))
     ;; TODO: Run tests.
     (build-system emacs-build-system)
     (inputs