Prevent skipping shards if a suggest builder is present

Even if the query part can rewrite to match none we can't skip the
suggest execution since it might yield results.

Relates to elastic#25658

Author: s1monw

core/src/main/java/org/elasticsearch/search/SearchService.java

@@ -854,8 +854,13 @@ public boolean canMatch(ShardSearchRequest request) throws IOException {
         }
     }
 
+    /**
+     * Returns true iff the given search source builder can be early terminated by rewriting to a match none query. Or in other words
+     * if the execution of a the search request can be early terminated without executing it. This is for instance not possible if
+     * a global aggregation is part of this request or if there is a suggest builder present.
+     */
     public static boolean canRewriteToMatchNone(SearchSourceBuilder source) {
-        if (source == null || source.query() == null || source.query() instanceof MatchAllQueryBuilder) {
+        if (source == null || source.query() == null || source.query() instanceof MatchAllQueryBuilder || source.suggest() != null) {
             return false;
         } else {
             AggregatorFactories.Builder aggregations = source.aggregations();

core/src/test/java/org/elasticsearch/search/SearchServiceTests.java

@@ -56,6 +56,7 @@
 import org.elasticsearch.search.internal.AliasFilter;
 import org.elasticsearch.search.internal.SearchContext;
 import org.elasticsearch.search.internal.ShardSearchLocalRequest;
+import org.elasticsearch.search.suggest.SuggestBuilder;
 import org.elasticsearch.test.ESSingleNodeTestCase;
 
 import java.io.IOException;
@@ -354,5 +355,11 @@ public void testCanRewriteToMatchNone() {
         assertTrue(SearchService.canRewriteToMatchNone(new SearchSourceBuilder().query(new TermQueryBuilder("foo", "bar"))));
         assertTrue(SearchService.canRewriteToMatchNone(new SearchSourceBuilder().query(new MatchNoneQueryBuilder())
             .aggregation(new TermsAggregationBuilder("test", ValueType.STRING).minDocCount(1))));
+        assertFalse(SearchService.canRewriteToMatchNone(new SearchSourceBuilder().query(new MatchNoneQueryBuilder())
+            .aggregation(new TermsAggregationBuilder("test", ValueType.STRING).minDocCount(1))
+            .suggest(new SuggestBuilder())));
+        assertFalse(SearchService.canRewriteToMatchNone(new SearchSourceBuilder().query(new TermQueryBuilder("foo", "bar"))
+            .suggest(new SuggestBuilder())));
+
     }
 }