Candidate fix for the nested aggregate query problem of ticket
[c2ad16f997ee9c8e].

FossilOrigin-Name: f3dd1fafd4718558de1f06139419a8c560d727f5
diff --git a/src/expr.c b/src/expr.c
index 10d9f77..95c3515 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3965,7 +3965,9 @@
       return WRC_Prune;
     }
     case TK_AGG_FUNCTION: {
-      if( !sqlite3FunctionUsesOtherSrc(pExpr, pSrcList) ){
+      if( (pNC->ncFlags & NC_InAggFunc)==0
+       && !sqlite3FunctionUsesOtherSrc(pExpr, pSrcList)
+      ){
         /* Check to see if pExpr is a duplicate of another aggregate 
         ** function that is already in the pAggInfo structure
         */
@@ -4002,8 +4004,8 @@
         ExprSetIrreducible(pExpr);
         pExpr->iAgg = (i16)i;
         pExpr->pAggInfo = pAggInfo;
-        return WRC_Prune;
       }
+      return WRC_Prune;
     }
   }
   return WRC_Continue;