fetch2/git: Add sanity check to ensure we really did fetch the correct revisions

The fetcher made the rather bold assumption that if it fetched from the upstream,
the revisions were present and correct. These checks are fast and ensure that
really is the case. The avoids accidental network accessed and missing
branch configuration problems.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
hob: changes to INHERIT var should use "append" operation

Setting INHERIT var means to remove other operations made on INHERIT.
This is too intrusive, so we decided to use append for this case.

[YOCTO #5448]
Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
toaster: exclude "set in documentation.conf" from variable history

That has no impact on the builds themselves, so we should just
remove that line from the variable history.

[YOCTO #5561]
Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>