The server side support; this is just the very low level, and the
caller needs to know which band it wants to send things out.
Signed-off-by: Junio C Hamano <junkio@cox.net>
(cherry picked from b786552b67878c7780c50def4c069d46dc54efbe commit)
This moves the receiver side of the sideband support from
fetch-clone.c to sideband.c and its header file, so that
archiver protocol can use it.
Signed-off-by: Junio C Hamano <junkio@cox.net>