[CentOS] centos 6.3 git core.sharedRepository = group/all not working?

HI

I have a git bare repo on centos 6.3 ( with selinux off)

the config is:
[core]
     repositoryformatversion = 0
     filemode = true
     bare = true
     sharedRepository = all  ( or true or group)


chmod -R g+rs objects

when  git pushed the changes from remote ssh .

the new file under objects are not writable.
e.g.:

-r--r--r--. 1 myuser mygroup 156 Jan 29 22:22 
objects/fa/905054c795a3b7e5c244bfc6f3a30a0277c6d0

what could be wrong?


thanks.

min