Windows 10 upgrade messes with linux partitions

We have a machine that was dual-boot between Windows 8 and Ubuntu 15.04.

Windows 8 offered to do a free upgrade to Windows 10. We accepted and then the machine rebooted to "grub rescue>" and neither OS was available.

I tried to return the partition types to normal by booting Fedora 22 from a usb stick and using the gnome disk utility, but that did not allow either OS to boot.

I ended up having to use the disk utility to put the partition types back to all Windows and then booting from an Ubuntu live disk that could install the Boot-Repair application. I ran that and allowed it to make the recommended changes. That allowed the Windows upgrade to proceed.

I still haven't done the next step of trying to restore the Ubuntu partitions and the master boot record. Right now it just boots into Windows, but it appears that I can take another step to try to restore Ubuntu.

http://askubuntu.com/questions/655011/windows-10-upgrade-kills-grub-and-boot-repair-doesnt-help