Add commit link and diff to RPM build job logs

The output of update_rpms.py is terse, making it difficult to verify its
actions.  Add a commit link and "git show" output to the log of every CI
job running the update_rpms.py script in "build" mode to facilitate
double-checking its actions.

(cherry picked from commit 6d51073f22)

.gitlab-ci.yml

@@ -1969,8 +1969,14 @@ assign-milestones:
 
 # Jobs to update RPMs
 
-.rpm-build-job: &rpm_build_job
+.rpm-build-job-common: &rpm_build_job_common
   <<: *manual_release_job_qa
+  after_script:
+    - git -C bind/ remote get-url origin | sed "s|\.git$|/-/commit/$(cat commit.txt)|"
+    - git -C bind/ show --color "$(cat commit.txt)" | sed "s|^$| |"
+
+.rpm-build-job: &rpm_build_job
+  <<: *rpm_build_job_common
   needs:
     - job: publish
       artifacts: false
@@ -1979,7 +1985,7 @@ assign-milestones:
       "${CI_PROJECT_DIR}"/bind9-qa/releng/update_rpms.py build --service "${SERVICE}" --version "${CI_COMMIT_TAG}"
 
 .rpm-build-job-private: &rpm_build_job_private
-  <<: *manual_release_job_qa
+  <<: *rpm_build_job_common
   needs:
     - job: publish-private
       artifacts: true