!!! git pull error in /usr/portage

I need help, when I run the --sync command this error

> calculate jefferson # emerge --sync
> >>> Syncing repository 'gentoo' into '/usr/portage'...
> /usr/bin/git pull
> You are not currently on a branch.
> Please specify which branch you want to merge with.
> See git-pull(1) for details.
> 
> git pull <remote> <branch>
> 
> !!! git pull error in /usr/portage
> calculate jefferson # 
>

Captura_de_tela_2017-01-22_03-09-34.png

Hi,use cl-update