[coreboot] push error (not Signed-off-by author/committer/uploader in commit message footer)

[WANG Siyuan]

Hi,
I push code as normal, but I got this error:
$ git push
Counting objects: 27, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (15/15), done.
Writing objects: 100% (15/15), 3.56 KiB, done.
Total 15 (delta 13), reused 0 (delta 0)
remote: Resolving deltas: 100% (13/13)
remote: Processing changes: refs: 1, done
To ssh://Siyuan@review.coreboot.org:29418/coreboot
  ! [remote rejected] HEAD -> refs/for/master (not Signed-off-by 
author/committer/uploader in commit message footer)
error: failed to push some refs to 
'ssh://Siyuan@review.coreboot.org:29418/coreboot'

My commit message is:
commit 9df9e354dee0f07569adfd69976d27e30fd99710
Author: WANG Siyuan <wangsiyuanbuaa at gmail.com>
Date:   Fri Jun 5 13:22:44 2015 +0800

     update submodule when 'make' rather than 'make menuconfig'

     'git submodule update --init' runs before 'make menuconfig'.
     This is very inconvenience when developing.
     CONFIG_USE_BLOBS is used to control updating submodule,
     but the original command is wrong.
     With this patch, people can choose 'Allow use of binary-only 
repository'
     if they want to update submodule.

     Change-Id: I4b49f9b0d258ba22a006b6e669bf7fa016ecd76c
     Signed-off-by: WANG Siyuan <SiYuan.Wang at amd.com>
     Signed-off-by: WANG Siyuan <wangsiyuanbuaa at gmail.com>

What is the problem? Thanks a lot.