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, 8 insertions, 1 deletions

diff --git a/tests/guix-git-authenticate.sh b/tests/guix-git-authenticate.sh
index 7b8951b9aaf..6cbb7b59c1f 100644
--- a/tests/guix-git-authenticate.sh
+++ b/tests/guix-git-authenticate.sh
@@ -1,5 +1,5 @@
 # GNU Guix --- Functional package management for GNU
-# Copyright © 2020, 2022, 2024 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2020, 2022, 2024-2025 Ludovic Courtès <ludo@gnu.org>
 #
 # This file is part of GNU Guix.
 #
@@ -53,6 +53,13 @@ guix git authenticate				\
      --cache-key="$cache_key" --stats           \
      --end="$v1_2_0_commit"
 
+# Likewise, but pass the OID of the annotated tag 'v1.2.0' instead of that of
+# the commit--this mimics what the pre-push hook gets when pushing tags.
+v1_2_0_annotated_tag="d5b556eef57321d0be89fdb07db447b2db2718ed"
+guix git authenticate                           \
+     --cache-key="$cache_key" --stats           \
+     --end="$v1_2_0_annotated_tag"
+
 rm "$XDG_CACHE_HOME/guix/authentication/$cache_key"
 
 # Commit and signer of the 'v1.0.0' tag.