In case of empty checksum type, emit validated.

src/libsync/transmissionchecksumvalidator.cpp

@@ -100,7 +100,10 @@ void TransmissionChecksumValidator::downloadValidation( const QByteArray& checks
 {
     // if the incoming header is empty, there was no checksum header, and
     // no validation can happen. Just continue.
-    if( checksumHeader.isEmpty() ) {
+    const QString csType = checksumType();
+
+    // for empty checksum type, everything is valid.
+    if( csType.isEmpty() ) {
         emit validated();
         return;
     }