git authenticate: Gracefully handle passing an annotated tag to ‘--end’.

Partly fixes <https://issues.guix.gnu.org/74583>.

Previously, passing an annotated tag to ‘--end’, as can happen when
‘guix git authenticate’ is invoked by the pre-push hook when pushing
tags, would lead to an error:

  guix git: error: Git error: the requested type does not match the type in the ODB

* guix/scripts/git/authenticate.scm (ensure-commit-id): New procedure.
(guix-git-authenticate): Use it.
* tests/guix-git-authenticate.sh: Test with $v1_2_0_annotated_tag.

Change-Id: I22e8eb665609522c80c1f0dcb9e77a46c23c0c3c

1 files changed, 9 insertions, 1 deletions

diff --git a/guix/scripts/git/authenticate.scm b/guix/scripts/git/authenticate.scm
index 3bc72a70b1..5f05428461 100644
--- a/guix/scripts/git/authenticate.scm
+++ b/guix/scripts/git/authenticate.scm
@@ -233,6 +233,14 @@ known-broken version is installed."
         (display %pre-push-hook port)
         (chmod port #o755)))))
 
+(define (ensure-commit-id repository oid)
+  "If OID refers to an annotated tag, return its target commit; otherwise
+return OID."
+  (let ((obj (object-lookup repository oid)))
+    (if (= OBJ-TAG (object-type obj))
+        (tag-target-id (tag-lookup repository oid))
+        oid)))
+
 (define (show-stats stats)
   "Display STATS, an alist containing commit signing stats as returned by
 'authenticate-repository'."
@@ -337,7 +345,7 @@ expected COMMIT and SIGNER~%")))
             (end         (match (assoc-ref options 'end-commit)
                            (#f  (reference-target
                                  (repository-head repository)))
-                           (oid oid)))
+                           (oid (ensure-commit-id repository oid))))
             (history     (match (assoc-ref options 'historical-authorizations)
                            (#f '())
                            (file (call-with-input-file file