fix for issue 183 (sftp.RemoteFile.ReadAheadRemoteFileInputStream) (revised)

src/main/java/net/schmizz/sshj/sftp/RemoteFile.java

@@ -89,7 +89,8 @@ public class RemoteFile
             throws IOException {
         return requester.request(newRequest(PacketType.WRITE)
                                          .putUInt64(fileOffset)
-                                         .putUInt32(len - off)
+                                        // TODO The SFTP spec claims this field is unneeded...? See #187
+                                         .putUInt32(len)
                                          .putRawBytes(data, off, len)
         );
     }