4.2 regression: ReactOS crashes on boot

In QEMU 4.1.x and earlier, ReactOS can successfully boot, but starting with 4.2, it fails, instead coming up with an error "The video driver failed to initialize."

This happens regardless of VM configuration (even -M pc-i440fx-4.1) and it works well with older versions of QEMU. bisecting QEMU to find the first bad commit reveals 0221d73ce6a8e075adaa0a35a6ef853d2652b855 as the culprit, which is updating the seabios version; perhaps this bug belongs there, but I don't know the appropriate avenue (it seems seabios is a subproject of QEMU anyway?).