bugzilla-tool supported it by "bugzilla-tool post-commits -b n HEAD"
I have to run "git reset" for webkit-patch for now.
post-commits still works fine.
However, "upload" doesn't support git commits yet.
webkit-patch help --all-commands
for a full list of commands.
Oh, I thought post-commits was replaced with upload.
Sorry for that.
Ojan fixed this.