[coreboot] git/gerrit question

[Oskar Enoksson]

I'm trying to upload a patch. It seems that for some reason "gerrit" 
requires a "signed-off-by" line in every single local commit in order to 
push it to the remote location. I'm able to "amend" such a line to the 
very last commit, but I can't find a way to do it on the previous 
commits. How can I do it? I've googled the web, browsed the manuals, 
scimmed through the tutorials and found no clue. Do I have to start from 
scratch?