AutoML PipelineSuggester: don't recommend pipelines from first-stage trainers that failed (#3593)

Author: daholste

src/Microsoft.ML.Auto/PipelineSuggesters/PipelineSuggester.cs

@@ -91,8 +91,8 @@ private static IEnumerable<SuggestedTrainer> GetTopTrainers(IEnumerable<Suggeste
             IEnumerable<SuggestedTrainer> availableTrainers,
             bool isMaximizingMetric)
         {
-            // narrow history to first stage runs
-            history = history.Take(availableTrainers.Count());
+            // narrow history to first stage runs that succeeded
+            history = history.Take(availableTrainers.Count()).Where(x => x.RunSucceded);
 
             history = history.GroupBy(r => r.Pipeline.Trainer.TrainerName).Select(g => g.First());
             IEnumerable<SuggestedPipelineRunDetail> sortedHistory = history.OrderBy(r => r.Score);