Assume no search instability and do NegaScout.

Did not have any search instability in the benchmark tests,
so I'll assume this either does not occur or is so rare its not an
issue.

src/search.cpp

@@ -385,8 +385,8 @@ void Search::search_root(Depth depth, int alpha, int beta) {
 
             if (value > alpha and value < beta) {
                 // PV search failed high, need to do a research.
-                int value2 = -search(depth - 1, -beta, -value, ply + 1);
-                value = std::max(value, value2);
+                // Assuming no instability, and using the new limit.
+                value = -search(depth - 1, -beta, -value, ply + 1);
             }
         }
         // First move - search fully.
@@ -550,8 +550,8 @@ int Search::search(Depth depth, int alpha, int beta, int ply) {
 
                 if (value > alpha and value < beta) {
                     // PV search failed high, need to do a research.
-                    int value2 = -search(depth - 1, -beta, -value, ply + 1);
-                    value = std::max(value, value2);
+                    // Assuming no instability, and using the new limit.
+                    value = -search(depth - 1, -beta, -value, ply + 1);
                 }
             } else {
                 // First move - do full search.