When Debian updated to GRUB 2 (package
grub-pc), it didn't automatically upgrade the MBR. Instead it configured the old GRUB 1 installation so that it will chainload GRUB 2; that way administrators can test the new GRUB 2 configuration. If GRUB 2 failed for some reason, you still were able to boot the system with one of the old GRUB 1 entries. After testing GRUB 2 you were supposed to run
upgrade-from-grub-legacy to replace the MBR, and then manually delete
Unfortunately, we didn't really do that on a lot of our servers, so now we have a mix of GRUB 1 and GRUB 2 MBRs, and we don't know which server is using which version. Is there any way to detect the GRUB MBR version?