Qt svg icon engine does not support multiple png icons

I create icon in such way:

QIcon icon;
icon.addFile( "icon.svg", QSize() );
icon.addFile( "icon16.png", QSize( 16, 16 ) );
icon.addFile( "icon32.png", QSize( 32, 32 ) );
icon.addFile( "icon64.png", QSize( 64, 64 ) );

Then I use it:
QPixmap p = icon.pixmap( 16 );
QPixmap p = icon.pixmap( 32 );
QPixmap p = icon.pixmap( 64 );
QPixmap p = icon.pixmap( 256 );

In all cases icon engine (not sure about 64) returns svg converted to pixmap. I expect to have png in first three situations.

The reason is probably addedPixmaps hash map in QSvgIconEngine which hashes using only icon mode and state and ignores size.