That's how I did it yesterday ... worked like a charm ... if you do it the first time ... the make command might take some minutes be sure to let it run till it gets you back to the command line ...
...
8. How to update on the most actual chainminer version (gitpull)?... first .. if it ain't broke don't fix it ...do backup of your actual bitfury chainminer version...
pi@bitfury ~ $ cp -a /opt/bitfury /usr/bitfury.backup
Then move to chainminer get latest version clean make ... restart ...
pi@bitfury ~ $ cd /opt/bitfury/chainminer
pi@bitfury ~ $ git pull
pi@bitfury ~ $ make clean
pi@bitfury ~ $ make
restart the miner ... and hope it will still hash ... :-)
...