send-pack: typofix error message

The message identifies the process as receive-pack when it cannot fork the
sideband demultiplexer. We are actually a send-pack.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/send-pack.c

@@ -334,7 +334,7 @@ int send_pack(struct send_pack_args *args,
 		demux.data = fd;
 		demux.out = -1;
 		if (start_async(&demux))
-			die("receive-pack: unable to fork off sideband demultiplexer");
+			die("send-pack: unable to fork off sideband demultiplexer");
 		in = demux.out;
 	}