dbnodeupdate.sh post upgrade step fails on Exadata storage software 12.1.2.1.1

I've done several Exadata deployments in the past two months and had to upgrade the Exadata storage software on half of them. Reason for that was because units shipped before May had their Exadata storage software version of 12.1.2.1.0.

The upgrade process of the database nodes ran fine but when I ran dbnodeupdate.sh -c for completing post upgrade steps I got an error that the system wasn't on the expected Exadata release or kernel:

(*) 2015-06-01 14:21:21: Verifying GI and DB's are shutdown
(*) 2015-06-01 14:21:22: Verifying firmware updates/validations. Maximum wait time: 60 minutes.
(*) 2015-06-01 14:21:22: If the node reboots during this firmware update/validation, re-run './dbnodeupdate.sh -c' after the node restarts..
(*) 2015-06-01 14:21:23: Collecting console history for diag purposes

ERROR: System not on expected Exadata release or kernel, exiting


ERROR: Correct error, or to override run: ./dbnodeupdate.sh -c -q -t 12.1.2.1.1.150316.2

Indeed, the database node was running the new Exadata software but still using the old kernel (2.6.39-400.243) and dbnodeupdate was expecting me to run the new 2.6.39-400.248 kernel:

imageinfo: 
Kernel version: 2.6.39-400.243.1.el6uek.x86_64 #1 SMP Wed Nov 26 09:15:35 PST 2014 x86_64 
Image version: 12.1.2.1.1.150316.2 
Image activated: 2015-06-01 12:27:57 +0100 
Image status: success 
System partition on device: /dev/mapper/VGExaDb-LVDbSys1

The reason for that was that the previous run of dbnodeupdate installed the new kernel package but failed to update grub.conf. The solution is to manually add the missing kernel entry to grub.conf and reboot the server to pick up the new kernel, here is a note for more information which by the time I had this problem was still internal:
Dbnodeupdate.sh Finishes With Error: System Not On Expected Exadata Release Or Kernel, Exiting (Doc ID 2007282.1)
Bug 20708183 - DOMU:GRUB.CONF KERNEL NOT ALWAYS UPDATED GOING TO 121211, NEW KERNEL NOT BOOTED