ci: ignore PR lookup failures in ocv track bump

Author: github-actions[bot]

.github/workflows/sync-upstream.yml

@@ -51,8 +51,13 @@ jobs:
           fi
 
           prs=$(mktemp)
-          git log --first-parent --reverse --format='%H' "$previous"..HEAD | while read -r sha; do
-            gh api "repos/${{ github.repository }}/commits/$sha/pulls" -q '.[] | select(.base.ref == "ocv") | "#\(.number) \(.title)"' || true
+          git fetch origin ocv
+          scan_ref=$(git rev-parse --verify --quiet origin/ocv >/dev/null && printf origin/ocv || printf HEAD)
+          git log --first-parent --reverse --format='%H' "$previous..$scan_ref" | while read -r sha; do
+            pull_requests=$(gh api "repos/${{ github.repository }}/commits/$sha/pulls" -q '.[] | select(.base.ref == "ocv") | "#\(.number) \(.title)"' 2>/dev/null || true)
+            if [ -n "$pull_requests" ]; then
+              printf '%s\n' "$pull_requests"
+            fi
           done | awk '!seen[$1]++' > "$prs"
 
           if [ ! -s "$prs" ]; then