git cherry-pick fails when picking a non-ff commit that is empty.  The advice
given with the failure is that a git-commit --allow-empty should be issued to
explicitly add the empty commit during the cherry pick.  This option allows a
user to specify before hand that they want to keep the empty commit.  This
eliminates the need to issue both a cherry pick and a commit operation.
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>