The C-c C-a binding in the change description is for Ack

and not for toggling amend.
Merge pull request #1308 from dachary/wip-c-c-c-a

The C-c C-a binding in the change description is for Ack
magit-commit-add-log: bugfix

As suggested by Daniel Dehennin in #1309.
Merge branch 'master' into next