Clear fd after closing to avoid double-close error

In send_pack(), clear the fd passed to pack_objects() by setting
it to -1, since pack_objects() closes the fd (via a call to
run_command()).  Likewise, in get_pack(), clear the fd passed to
run_command().

Not doing so risks having git_transport_push(), caller of
send_pack(), closing the fd again, possibly incorrectly closing
some other open file; or similarly with fetch_refs_from_pack(),
indirect caller of get_pack().

Signed-off-by: Jens Lindström <jl@opera.com>
Acked-by: Jeff King <peff@peff.net>
Acked-by: Duy Nguyen <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fetch-pack.c

@@ -776,6 +776,10 @@ static int get_pack(struct fetch_pack_args *args,
 		close(cmd.out);
 	}
 
+	if (!use_sideband)
+		/* Closed by start_command() */
+		xd[0] = -1;
+
 	ret = finish_command(&cmd);
 	if (!ret || (args->check_self_contained_and_connected && ret == 1))
 		args->self_contained_and_connected =

send-pack.c

@@ -300,8 +300,12 @@ int send_pack(struct send_pack_args *args,
 				shutdown(fd[0], SHUT_WR);
 			if (use_sideband)
 				finish_async(&demux);
+			fd[1] = -1;
 			return -1;
 		}
+		if (!args->stateless_rpc)
+			/* Closed by pack_objects() via start_command() */
+			fd[1] = -1;
 	}
 	if (args->stateless_rpc && cmds_sent)
 		packet_flush(out);