The fourth argument of strbuf_splice() is passed to memcpy(3), which is
not supposed to handle NULL pointers. Let's be extra careful and use a
valid empty string instead. It even shortens the source code. :)
Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>