Bug#816447: QImage ignore headers of jpg files

[Strelok <strelkov355@gmail.com>]

Package: qtcreator
Version: 3.2.1

http://doc.qt.io/qt-4.8/qimage.html say "If the format is not
specified (which is the default), the loader probes the file for a
header to guess the file format.". Okay. I'm load any jpg file. Then,
rename this file into "test.png". After this I'm run simple test:

#include<QImage>
#include<cassert>

int main(int argc, char *argv[])
{
    QImage test("test.png");
    assert(!test.isNull());
    return 0;
}

...SIGABRT. "Loader probes the file for a header"? Filename extension
is not a header. And yes, if jpg file have ".jpg" extension, I'm don't
get SIGABRT signal.

PS Same result in 3.6.0.