LUCENE-9555 Ensure scorerIterator is fresh for opt

Some collectors provide iterators that can efficiently skip
non-competitive docs. When using DefaultBulkScorer#score function
we create a conjunction of scorerIterator and collectorIterator.
As collectorIterator always starts from a docID = -1,
and for creation of conjunction iterator we need all of its
sub-iterators to be on the same doc, the creation of conjuction
iterator will fail if scorerIterator has already been advanced
to some other document.

This patch ensures that we create conjunction between scorerIterator
and collectorIterator only if scorerIterator has not been advanced yet.

Relates to apache#1725
Relates to apache#1937

lucene/CHANGES.txt

@@ -142,6 +142,9 @@ Improvements
 
 Bug fixes
 
+* LUCENE-9555: For sort optimization, create conjunction between scorerIterator
+  and collectorIterator only if scorerIterator has not been advanced yet. (Mayya Sharipova)
+
 * LUCENE-8663: NRTCachingDirectory.slowFileExists may open a file while 
   it's inaccessible. (Dawid Weiss)
 

lucene/core/src/java/org/apache/lucene/search/Weight.java

@@ -203,10 +203,16 @@ public long cost() {
     public int score(LeafCollector collector, Bits acceptDocs, int min, int max) throws IOException {
       collector.setScorer(scorer);
       DocIdSetIterator scorerIterator = twoPhase == null ? iterator : twoPhase.approximation();
-      DocIdSetIterator collectorIterator = collector.competitiveIterator();
-      // if possible filter scorerIterator to keep only competitive docs as defined by collector
-      DocIdSetIterator filteredIterator = collectorIterator == null ? scorerIterator :
-          ConjunctionDISI.intersectIterators(Arrays.asList(scorerIterator, collectorIterator));
+
+      DocIdSetIterator filteredIterator = scorerIterator;
+      if (scorerIterator.docID() == -1) {
+        DocIdSetIterator collectorIterator = collector.competitiveIterator();
+        if (collectorIterator != null) {
+          // filter scorerIterator to keep only competitive docs as defined by collector
+          filteredIterator = ConjunctionDISI.intersectIterators(Arrays.asList(scorerIterator, collectorIterator));
+        }
+      }
+
       if (filteredIterator.docID() == -1 && min == 0 && max == DocIdSetIterator.NO_MORE_DOCS) {
         scoreAll(collector, filteredIterator, twoPhase, acceptDocs);
         return DocIdSetIterator.NO_MORE_DOCS;