Only list slugs from the newest commit in the book autocomplete list
A more long-term solution might be to switch around the version and book input boxes, so that it is intuitive to enter version before book, have version default to main, and have the frontend query for the slugs based on repository and version.
Current version
Lists all books known to have existed in any version of the repository
New version:
Lists books that exist in the newest commit on the repository (regardless of branch)
fixes openstax/ce#2232
A more long-term solution might be to switch around the version and book input boxes, so that it is intuitive to enter version before book, have version default to main, and have the frontend query for the slugs based on repository and version.
Current version
Lists all books known to have existed in any version of the repository
New version:
Lists books that exist in the newest commit on the repository (regardless of branch)