[PATCH] defaults for where to merge from (take 2)

I'd rather remove the complete section (However, that means that you have 
to introduce a function to do that in config.c)

No problem.

Also, the second part of your patch would be clearer (methinks) if you 
replaced the call to get_sha1() with dwim_ref(). You'd get the real 
refname for free...

Not only that, my previous version did not work if somebody specified
remotes/remote/upstreambranch instead of remote/upstreambranch.

Updated version attached.

Paolo