While investigating another grub issue, I was confused by the path
taken in the logs reported, and noticed that on a ramdisk, we might
not actually have a valid response to os.path.ismount, I'm guessing
depending on what in memory filesystem is in use while also coupled
with attempting to check a filesystem.
Adds a test to validate that exceptions raised on these commands
where this issue can be encountered, are properly bypassed, and also
adds additional logging to make it easier to figure out what is
going on in the entire bootloader setup sequence.
Change-Id: Ibd3060bef2e56468ada6b1a5c1cc1632a42803c3
e5d552474b