[gentoo-user] problem with emerge --sync

[Jack <ostroffjh@users.sourceforge.net>]

I had no problem updating my system two or three days ago, but today  
when I try to update, I get:

>>> Syncing repository 'gentoo' into '/var/db/repos/gentoo'...
Auto packing the repository for optimum performance.
See "git help gc" for manual housekeeping.
Enumerating objects: 175170, done.
Counting objects: 100% (175170/175170), done.
Delta compression using up to 16 threads
Compressing objects: 100% (128856/128856), done.
fatal: unable to read de2a1e7d166bc5b3508bbe91e7bef61324ac3183
fatal: failed to run repack
!!! git gc error in /var/db/repos/gentoo

The sync for all other repositories is fine, and I get the same using  
"eix-sync" "emerge --sync" or "emaint sync"

If I "cd /var/db/repos/gentoo/" and then "git status I get

On branch stable
Your branch and 'origin/stable' have diverged,
and have 1 and 1 different commits each, respectively.
   (use "git pull" if you want to integrate the remote branch with  
yours)

nothing to commit, working tree clean

Doing "git fsck --full" gives me "missing blob  
de2a1e7d166bc5b3508bbe91e7bef61324ac3183:" as well as many dangling  
commits.

I'd love to know what happened, but more important is whether there is  
a way to recover from this, or should I just remove and re-add the  
repository with eselect repository?

Jack