If receive.denyNonFastforwards is set to true, git-receive-pack will deny
non fast-forwards, i.e. forced updates. Most notably, a push to a repository
which has that flag set will fail.
As a first user, 'git-init-db --shared' sets this flag, since in a shared
setup, you are most unlikely to want forced pushes to succeed.
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Junio C Hamano <junkio@cox.net>