gistfile1.txt

1. Boot up the VM with 15.10 server iso (amd64)
2. When presented with the Language selection, hit ESC button on the keyboard, you'll drop out to the grub menu w/ inputs like "Install Ubuntu server", etc.
3. Hit ESC button once again.  A pop-up window will appear, asking if you want to leave the graphical boot menu and start the text mode interface.
4. Press ENTER (while on OK button)
5. Now you see an invitation: "boot: _". Type in "/install/vmlinuz auto initrd=/install/initrd.gz" and press ENTER.

That's the the bug is: I'm going back to the GUI with Language selection

expected result: machine starts booting the installer in the text mode