receive-pack: release pack files before garbage-collecting

Before auto-gc'ing, we need to make sure that the pack files are
released in case they need to be repacked and garbage-collected.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -1796,6 +1796,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 				"gc", "--auto", "--quiet", NULL,
 			};
 			int opt = RUN_GIT_CMD | RUN_COMMAND_STDOUT_TO_STDERR;
+			close_all_packs();
 			run_command_v_opt(argv_gc_auto, opt);
 		}
 		if (auto_update_server_info)