Bug#822940: [powerpc] Debian Installer Stretch Alpha 6 release broken

[Mathieu Malaterre]

retitle 822940 [powerpc] Debian Installer Stretch Alpha 6 release broken
thanks

I can reproduce the issue on MacMini G4 using:

http://cdimage.debian.org/cdimage/stretch_di_alpha6/powerpc/iso-cd/debian-stretch-DI-alpha6-powerpc-netinst.iso