Fix test failure.

src/Renci.SshNet.Tests/Classes/Sftp/SftpFileStreamTest_CanRead_Closed_FileAccessRead.cs

@@ -24,7 +24,7 @@ namespace Renci.SshNet.Tests.Classes.Sftp
             var random = new Random();
             _path = random.Next().ToString();
             _handle = GenerateRandom(3, random);
-            _bufferSize = (uint) random.Next(0, 1000);
+            _bufferSize = (uint) random.Next(1, 1000);
             _readBufferSize = (uint) random.Next(0, 1000);
             _writeBufferSize = (uint) random.Next(0, 1000);
         }