buildhistory-diff: add option to compare actual signature differences
Use the code underpinning bitbake-diffsigs to add an option to
buildhistory-diff to determine and display the differences between the
actual signature inputs, with a twist - we collapse identical
changes across different tasks, showing only the most recent task to
have that difference, meaning that there's less noise to wade through
when you just want to know what changed in order to cause some
rebuilding you're seeing.
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
