Different merges from translation perspective

[Alexander Shopov]

Hi all,
What is the difference between simple, fast forward, automatic and
trivial merge?
I am updating the translation and the only thing I am sure about is
that these four are not octopus merges,
Fast forward is when current state is ancestor of tip, automatic merge
is when the merge algorithm is decided by git rather than developer.
What about simple (git-merge-octopus.sh) and trivial
(builtin/merge.c)?
Kind regards:
al_shopov