fix #934 - try to avoid exposing AggregateException unnecessarily

src/StackExchange.Redis/ConnectionMultiplexer.cs

@@ -566,8 +566,15 @@ internal bool TryResend(int hashSlot, Message message, EndPoint endpoint, bool i
         public void Wait(Task task)
         {
             if (task == null) throw new ArgumentNullException(nameof(task));
+            try
+            {
                 if (!task.Wait(TimeoutMilliseconds)) throw new TimeoutException();
             }
+            catch (AggregateException aex) when (IsSingle(aex))
+            {
+                throw aex.InnerExceptions[0];
+            }
+        }
 
         /// <summary>
         /// Wait for a given asynchronous operation to complete (or timeout)
@@ -577,10 +584,23 @@ public void Wait(Task task)
         public T Wait<T>(Task<T> task)
         {
             if (task == null) throw new ArgumentNullException(nameof(task));
+            try
+            {
                 if (!task.Wait(TimeoutMilliseconds)) throw new TimeoutException();
+            }
+            catch (AggregateException aex) when (IsSingle(aex))
+            {
+                throw aex.InnerExceptions[0];
+            }
             return task.Result;
         }
 
+        private static bool IsSingle(AggregateException aex)
+        {
+            try { return aex != null && aex.InnerExceptions.Count == 1; }
+            catch { return false; }
+        }
+
         /// <summary>
         /// Wait for the given asynchronous operations to complete (or timeout)
         /// </summary>