Bury failed nightly releases as prereleases (#31348)

.github/workflows/nightly.yml

@@ -41,21 +41,32 @@ jobs:
 
   publish-nightly-release:
     # This job is only useful when run on upstream servo.
-    if: github.repository == 'servo/servo' || github.event_name == 'workflow_dispatch'
+    if: always() && (github.repository == 'servo/servo' || github.event_name == 'workflow_dispatch')
     name: Publish GH Release for nightly
     runs-on: ubuntu-20.04
     steps:
-      - run: |
+      - name: Publish as latest (success)
+        if: success()
+        run: |
           gh api \
             --method PATCH \
             -H "Accept: application/vnd.github+json" \
             -H "X-GitHub-Api-Version: 2022-11-28" \
             /repos/${NIGHTLY_REPO}/releases/${RELEASE_ID} \
             -F draft=false
-        env:
-          GITHUB_TOKEN: ${{ secrets.NIGHTLY_REPO_TOKEN }}
-          NIGHTLY_REPO: ${{ github.repository_owner }}/servo-nightly-builds
-          RELEASE_ID: ${{ needs.create-draft-release.outputs.release-id }}
+      - name: Publish as latest (failure)
+        if: failure()
+        run: |
+          gh api \
+            --method PATCH \
+            -H "Accept: application/vnd.github+json" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            /repos/${NIGHTLY_REPO}/releases/${RELEASE_ID} \
+            -F prerelease=true -F draft=false
+    env:
+      GITHUB_TOKEN: ${{ secrets.NIGHTLY_REPO_TOKEN }}
+      NIGHTLY_REPO: ${{ github.repository_owner }}/servo-nightly-builds
+      RELEASE_ID: ${{ needs.create-draft-release.outputs.release-id }}
     needs:
       - create-draft-release
       - upload-linux