Fix background connection exception handling in Core

StackExchange.Redis.Core.sln

@@ -11,6 +11,7 @@ Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "StackExchange.Redis.Tests",
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{3AD17044-6BFF-4750-9AC2-2CA466375F2A}"
 	ProjectSection(SolutionItems) = preProject
+		global.json = global.json
 		NuGet.Config = NuGet.Config
 	EndProjectSection
 EndProject

StackExchange.Redis/StackExchange/Redis/PhysicalConnection.cs

@@ -32,6 +32,10 @@ private static Action<Task<int>> EndReadFactory(PhysicalConnection physical)
         {
             return result =>
             {   // can't capture AsyncState on SocketRead, so we'll do it once per physical instead
+                if (result.IsFaulted)
+                {
+                    GC.KeepAlive(result.Exception);
+                }
                 try
                 {
                     physical.Multiplexer.Trace("Completed asynchronously: processing in callback", physical.physicalName);