ganeti fix add ffadmin to sudo group

ganeti/files/hooks/40-ssh

@@ -11,7 +11,7 @@ echo "%sudo   ALL=(ALL:ALL) NOPASSWD: ALL" >> $TARGET/etc/sudoers
 
 # Add ffadmin user
 chroot "$TARGET" adduser --disabled-password --gecos "" ffadmin
-chroot "$TARGET" addgroup ffadmin sudo
+chroot "$TARGET" adduser ffadmin sudo
 
 # Configure ssh keys
 mkdir -p $TARGET/home/ffadmin/.ssh/