This speeds up parallel unit test runs from a very consistent 2:49 to
a very consistent 1:53, or a 33% reduction.
Signed-off-by: Ryan Davis <zenspider@chef.io>
* Fix `grub_conf` menuentry detection
This does the following:
- Corrects Grub2 bug where last entry was always selected
- Adds support for specifying a Grub2 menu entry by name
- Adds support for using `GRUB_DEFAULT=saved` with Grub2
- Adds more Unit tests
* Add error if menuentry name cannot be extracted
* Add handling for missing/unreadable grubenv
* Add defensive code for failed menuentry extraction
