[PATCH] nbtree: Do not show debugmessage if deduplication is disabled

Even though the message literally says whether the index "can safely" or
"cannot" use deduplication, the function specifically avoids the debug message
for system columns, so I think it also makes sense to hide it when
deduplication is turned off. 

diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 2f5f14e527..b78b542429 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -2710,6 +2710,9 @@ _bt_allequalimage(Relation rel, bool debugmessage)
     if (IsSystemRelation(rel))
         return false;
 
+    if (!BTGetDeduplicateItems(rel))
+        return false;
+
     for (int i = 0; i < IndexRelationGetNumberOfKeyAttributes(rel); i++)
     {
         Oid            opfamily = rel->rd_opfamily[i];
-- 
2.17.0