Fixing bug with ExtractSubDataset function not fully initializing subdataset (#390)

test/test_Reduce.cpp

@@ -14,7 +14,7 @@ namespace CorrectnessTests
 
         // Allocate data
         Dataset dataset;
-        dataset.Initialize(numDevices, numElements, dataType, inPlace);
+        dataset.Initialize(numDevices, numElements, dataType, inPlace, ncclCollReduce);
 
         // Test each possible root
         for (int root = 0; root < numDevices; root++)