Show path when directory delete fails in test setup

src/Microsoft.DotNet.TestFramework/TestAssetInstance.cs

@@ -50,9 +50,16 @@ namespace Microsoft.DotNet.TestFramework
             MigrationBackupRoot = new DirectoryInfo(Path.Combine(root.Parent.FullName, "backup"));
 
             if (Root.Exists)
+            {
+                try
                 {
                     Root.Delete(recursive: true);
                 }
+                catch (IOException ex)
+                {
+                    throw new InvalidOperationException("Unable to delete directory: " + Root.FullName, ex);
+                }
+            }
 
             Root.Create();