ci: add conversation filter, link logging, and error handling to auto-update-pr

Author: goastler

.github/workflows/auto-update-pr.yml

@@ -74,17 +74,23 @@ jobs:
 
           for n in "${prs[@]}"; do
             echo "::group::PR #$n"
+            echo "Considering https://github.com/$REPO/pull/$n"
 
             mergeable=""
             state=""
             # Poll until GitHub finishes computing the merge state (it is lazy
             # and returns UNKNOWN right after a base change).
             for attempt in $(seq 1 "$POLL_ATTEMPTS"); do
-              read -r mergeable state < <(
+              if ! out=$(
                 gh pr view "$n" --repo "$REPO" \
                   --json mergeable,mergeStateStatus \
                   --jq '"\(.mergeable) \(.mergeStateStatus)"'
-              )
+              ); then
+                echo "Failed to fetch merge state for PR #$n; skipping."
+                mergeable="UNKNOWN"; state="UNKNOWN"
+                break
+              fi
+              read -r mergeable state <<<"$out"
               echo "attempt $attempt: mergeable=$mergeable mergeStateStatus=$state"
               if [ "$mergeable" != "UNKNOWN" ] && [ "$state" != "UNKNOWN" ]; then
                 break
@@ -117,11 +123,46 @@ jobs:
               continue
             fi
 
-            echo "PR #$n is behind but passing. Updating its branch..."
-            gh api \
+            # Skip PRs with unresolved review conversations. A branch update
+            # won't unblock them, and we should not flywheel a PR that still has
+            # open feedback toward an auto-merge.
+            owner="${REPO%/*}"; name="${REPO#*/}"
+            if ! unresolved=$(
+              gh api graphql \
+                -f owner="$owner" -f name="$name" -F number="$n" \
+                -f query='
+                  query($owner:String!, $name:String!, $number:Int!) {
+                    repository(owner: $owner, name: $name) {
+                      pullRequest(number: $number) {
+                        reviewThreads(first: 100) {
+                          nodes { isResolved }
+                          pageInfo { hasNextPage }
+                        }
+                      }
+                    }
+                  }' \
+                --jq '[ .data.repository.pullRequest.reviewThreads.nodes[]
+                        | select(.isResolved == false) ] | length'
+            ); then
+              echo "Failed to fetch review threads for PR #$n; skipping."
+              echo "::endgroup::"
+              continue
+            fi
+            if [ "$unresolved" -gt 0 ]; then
+              echo "PR #$n has $unresolved unresolved conversation(s); skipping."
+              echo "::endgroup::"
+              continue
+            fi
+
+            echo "PR #$n is behind, passing, and has no open conversations. Updating its branch..."
+            if ! gh api \
               --method PUT \
               -H "Accept: application/vnd.github+json" \
-              "/repos/$REPO/pulls/$n/update-branch"
+              "/repos/$REPO/pulls/$n/update-branch"; then
+              echo "Failed to update PR #$n; skipping."
+              echo "::endgroup::"
+              continue
+            fi
 
             echo "Updated PR #$n. Done (one per run)."
             echo "::endgroup::"