git merge exit code semantics

Hi,

Is there any place I can find the semantics for exit code values for
'git-merge'? 

I would assume that '0' means merge was successful and '1' means there
was a conflict, but it doesn't state it (and should) in the
documentation.

After being confused by git-status, I felt I should ask.

If someone can explain it, I could probably cook up a patch for the
docs. 

David