How to merge FETCH_HEAD?

OK, I did a fetch and now I can see remote history by

$git log FETCH_HEAD

But, how to merge it?

$ git pull . FETCH_HEAD
error: no such remote ref refs/heads/FETCH_HEAD
Fetch failure: .

$git merge FETCH_HEAD
FETCH_HEAD - not something we can merge

So, how can I merge this without an extra fetch?

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MST