Bind has switched terminology from master/slave to primary/secondary.
When using this more modern terminology it makes sense to also change the names of the directories 'master' and 'slave' to 'primary' and 'secondary', which I did.
I would appreciate it if the make options for the port could include options like
(*) Use primary/secondary terminology
( ) User master/slave terminology
This would avoid the creation of new directories named 'master' and 'slave' when updating, as well as the installation of new 'empty.db' and 'localhost-*.db' files in unused directories. On the other hand, it would still allow existing installations to continue using the old terminology, if desired.
Since Bind now prefers the use of primary/secondary, it would probably also make sense to use these terms as the default for new installs.