gh: tests: use linked tag instead of branch in notif

To be able to save the cache, we need to use branches instead of tags.
But for the notif, it might be better to use the tag
(export/20240308T121027), not just the branch (export).

While at it, use the full check of the ref (just in case 'export' or
'export-net' tags are used), and put the URL at the end on IRC (not nice
output when the URL got a preview).

Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

.github/workflows/tests.yml

@@ -159,19 +159,34 @@ jobs:
           done
           echo "url=${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}" >> ${GITHUB_OUTPUT}
 
+      - name: get linked tag
+        if: github.ref == 'refs/heads/export' || github.ref == 'refs/heads/export-net'
+        id: tag
+        run: |
+          TAG=$(curl ${CURL_OPT} -H "${CURL_ACC}" -H "${CURL_AUTH}" "${URL}" | jq -r ".[] | select(.object.sha == \"${SHA}\").ref" | tail -n1)
+          echo "Found: ${TAG} (${SHA} - ${BRANCH})"
+          TAG="${TAG:10}"
+          echo "tag=${TAG:-${BRANCH}}" >> ${GITHUB_OUTPUT}
+        env:
+          CURL_AUTH: "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}"
+          URL: "${{ env.URI }}/repos/${{ github.repository }}/git/matching-refs/tags/"
+          SHA: "${{ github.sha }}"
+          BRANCH: "${{ github.ref_name }}"
+
       - name: irc tests
-        if: github.ref_name == 'export' || github.ref_name == 'export-net'
+        if: github.ref == 'refs/heads/export' || github.ref == 'refs/heads/export-net'
         uses: rectalogic/notify-irc@v2
         with:
           server: irc.libera.chat
           channel: "#mptcp-ci"
           nickname: gh-tests-bot
           verbose: true
           message: |-
-            New GH Actions Tests job validating ${{ github.ref_name }} (by ${{ github.actor }}) just ended: ${{ steps.test.outputs.url }}
+            New GH Actions Tests job validating ${{ steps.tag.outputs.tag }} (by ${{ github.actor }}) just ended:
             - ${{ steps.test.outputs.ccl_normal }}
             - ${{ steps.test.outputs.ccl_debug }}
             - ${{ steps.test.outputs.ccl_btf }}
+            - Task: ${{ steps.test.outputs.url }}
 
       - name: get commit info
         id: commit