Wrong error log when drive is specified qcow but qcow2 image file used.

On archlinux qemu version 4.0.0 when I type:

$ qemu-system-x86_64 -drive format=qcow,file=image.qcow2 ...

I get this output in stderr 

qemu-system-x86_64 -drive format=qcow,file=image.qcow2 ...: Unsupported qcow version 3

image.qcow2 is a qcow2 image created by qemu-img. error states that problem is with lack support with qcow3 format but real problem is that foramt=qcow is wrong option.