upload-pack: use object pointer not copy of sha1 to keep track of has/needs.
upload-pack: use object pointer not copy of sha1 to keep track of has/needs.

This does not change what happens in the command in any way, but
is to prepare for further work.

Signed-off-by: Junio C Hamano <dc50d1021234060e53ec42a77d526afa2fe07479@cox.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git