Git error

[Simon Peyton-Jones]

I got this message when pushing today

Simon

Syncing Git repo.
Finished applying...
Waiting for fcntl lock... 1
Counting objects: 11, done.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (6/6), 2.32 KiB, done.
Total 6 (delta 5), reused 0 (delta 0)
To git at github.com:ghc-hq/ghc.git
   a52b716..cced396  master -> master
error: Unable to append to .git/logs/refs/remotes/github/master: Permission denied
error: Cannot update the ref 'refs/remotes/github/master'.
Push successful.
(By the way, the remote repository has 4 patches to pull.)