send-pack: allow the same source to be pushed more than once.

The revised code accidentally inherited the restriction that a
reference can be pushed only once, only because the original did
not allow renaming.  This is no longer necessary so lift it.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

connect.c

@@ -190,13 +190,6 @@ static int match_explicit_refs(struct ref *src, struct ref *dst,
 		}
 		if (errs)
 			continue;
-		if (matched_src->peer_ref) {
-			errs = 1;
-			error("src ref %s is sent to more than one dst.",
-			      matched_src->name);
-		}
-		else
-			matched_src->peer_ref = matched_dst;
 		if (matched_dst->peer_ref) {
 			errs = 1;
 			error("dst ref %s receives from more than one src.",