A master page is created with the name 'master'. The site is built and all pages' use the master page via Page Properties > Miscellaneous.
Then later, having been struck by a moment of 'genius', the master page layout is intended to be modified to make it even more perfect (

The original master page is renamed to, say, 'master-old'. The cloned page is then renamed to 'master'.
All of the pages which pointed to the original master page are updated to now use 'master-old'.
Is there a quick and dirty way to change all of the pages' master page name back to 'master' replacing the 'master-old' name, or to prevent the pages from adopting the previous-now-renamed master page name?
Appreciate any/all help.