Merge master into fix branch during review

[Jeanette Winzenburg]

.. is something I _personally_ don't like: have to mentally sort the  
related from the unrelated commits in the history.

The contributing guidelines do allow intermediate merges (bolding by me)

"If you __need__ to pick up changes from master, you can merge master  
into your branch"

my interpretation would be: don't without good reason.

To merge or not to merge, that is the quesion :)

-- Jeanette