-# 'format': 'nbd' is not actually "correct", but this is probably the only way
-# to test bdrv_swap() on an NBD BDS
+# 'format': 'nbd' is not actually "correct", but this was the only way to
+# test the bug fixed in commit f53a829. Though the bug's related code
+# bdrv_swap() was replaced later, let's make sure we don't fall in the same
+# pit again.