add special "matching refs" refspec This patch provides a way to specify "push matching heads" using a special refspec ":". This is useful because it allows "push = +:" as a way to specify that matching refs will be pushed but, in addition, forced updates will be allowed, which was not possible before. Signed-off-by: Paolo Bonzini <bonzini@gnu.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>