QImageReader incorrectly set DevicePixelRatio to 1.0 for filenames containing a '.'

If you have an image whose filename contains a dot, QImageReader will incorrectly set the devicePixelRatio to 1.0 when it should be set to 2.0.

For example, when running these lines on a Mac with Retina screen, the pixmap will have its DevicePixelRatio set to 1.0:

QString fileName = QString(":/images/category.active@2x.png");
QPixmap pixmap = fileName;

The bug occurs in qimagereader.cpp:1372:

    if (!disable2xImageLoading && QFileInfo(fileName()).baseName().endsWith(QLatin1String("@2x"))) {
           image->setDevicePixelRatio(2.0);
    }

For a fileName like 

:/images/category.active@2x.png

the baseName will be "category" and as such the condition fails and the devicePixelRatio is not set to 2.0.