This makes it easier to obtain the difference from the last three
builds particularly where a single build might account for more than one
commit in the buildhistory git repository (e.g. if package and image
changes occurred).
(From OE-Core rev: 9512f3787295d662678c2943da31197c8df39e99)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>