... fails

$ git pull --rebase && git push
Current branch master is up to date.
To git@github.com:gentoo-science/sci.git
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'git@github.com:gentoo-science/sci.git'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes (e.g. 'git pull') before pushing again.  See the
'Note about fast-forwards' section of 'git push --help' for details.
Everything up-to-date

Why are they out of sync?  Did I do anything wrong?  What should be done
in this case?

Cheers,
Thomas

-- 
Thomas Kahle
http://dev.gentoo.org/~tomka/