Installer tries to install grub on the wrong partition

I have just installed Ubuntu 14.04 on a Dell precision M3800.
This gave me some headache installing grub, since during the install, the hard disk was assigned to /dev/sdb.
Installing the filesystem worked well, but the grub pat failed. No matter what I did, it always tried to install grub on /dev/sda

I ended up in continuing the intall without bootloader, and when finished, I escaped the install sequence and executed a shell where I executed this command:
grub-install --root-directory=/target /dev/sda

Thus I worked around the problem, but I think that this is an easily fixable bug in the installer that should be reported, but which component should it be reported against?

PS: I guess the cause of this behaviour, is that the USB stick which I use, does not contain a driver for the disk controller. Thus the driver module is first loaded when the USB gets network access and can fetch the driver from the net. Thus the USB is always assigned /dev/sda