test: fix two failing tests

replication/cluster.test.py would fail at server exit, because
at_exit() handler tries to destroy a cbus while its mutex is locked.

args.test.py would fail when run with 'make test'

src/cbus.c

@@ -183,6 +183,12 @@ cbus_create(struct cbus *bus)
 static void
 cbus_destroy(struct cbus *bus)
 {
+	/*
+	 * Lock the mutex to ensure we do not destroy a mutex
+	 * while it is locked, happens in at_exit() handler.
+	 */
+	(void) tt_pthread_mutex_lock(&bus->mutex);
+	(void) tt_pthread_mutex_unlock(&bus->mutex);
 	(void) tt_pthread_mutex_destroy(&bus->mutex);
 	(void) tt_pthread_cond_destroy(&bus->cond);
 	rmean_delete(bus->stats);

test/box-py/args.test.py

@@ -9,6 +9,7 @@ server.test_option("-h")
 # Replace with the same value for case when builddir inside source dir
 sys.stdout.push_filter(re.escape(os.getenv("BUILDDIR")+'/src/tarantool'), "tarantool")
 sys.stdout.push_filter(re.escape(os.getenv("BUILDDIR")), "${SOURCEDIR}")
+sys.stdout.push_filter(re.escape(os.getenv("SOURCEDIR")+'/src/tarantool'), "tarantool")
 sys.stdout.push_filter(re.escape(os.getenv("SOURCEDIR")), "${SOURCEDIR}")
 sys.stdout.push_filter("invalid option.*", "invalid option")
 sys.stdout.push_filter("unrecognized option.*", "unrecognized option")