Update CHANGES-jumbo and CREDITS-jumbo (and the .mailmap that helps producing
them).

git shortlog -w78,8,10 -n --no-merges 1.7.9-jumbo-7..HEAD |
sed -r 's/^ {8}/\t/; s/([^\t]) {2,}/\1 /g'

git shortlog -ns --no-merges 1.7.9-jumbo-7..HEAD | cut -f2- | sort -f